JP2010021580A - Magneto-resistance effect device, magnetic random access memory, electronic card, electronic apparatus, production process of magneto-resistance effect device, and production process of magnetic random access memory - Google Patents

Abstract

The present invention achieves high heat disturbance resistance of bit information even when miniaturized and realizes a large capacity.
A magnetoresistive element of the present invention has a nonmagnetic layer 13 between a recording layer 11 having perpendicular magnetization and a fixed layer 12, and a magnetic metal between the nonmagnetic layer 13 and the fixed layer 12. A layer 18 is provided, and a magnetic metal layer 19 is provided between the nonmagnetic layer 13 and the recording layer 11. The nonmagnetic layer 13 includes MgO with the (001) plane oriented, and the magnetic metal layers 18 and 19 have a magnetic property selected from Co, Fe, Co—Fe alloy, and Fe—Ni alloy with the (001) plane oriented. And at least one of the recording layer 11 and the fixed layer 12 includes a layer containing at least one of Fe, Co, and Ni, and Cr, Pt, Pd, Ir, Rh, Ru, Os, Re, Au, and Cu. Layers including at least one are alternately stacked, and the damping constant of the magnetic metal layer 19 is smaller than the damping constant of the recording layer 11.
[Selection] Figure 3

Description

  The present invention relates to a magnetoresistive effect element, a magnetic random access memory (MRAM), and an electronic card and an electronic device using the same.

  2. Description of the Related Art A magnetic random access memory (MRAM) using a tunneling magnetoresistive effect (TMR) is characterized in that data is stored according to the magnetization state of an MTJ (Magnetic Tunnel Junction) element. Regarding this magnetic random access memory, a number of techniques have been proposed for practical use.

  For example, a yoke wiring structure has been proposed for the purpose of reducing the write current. Further, regarding the structure of the MTJ element, there are a structure using a perpendicular magnetization film made of a GdFe alloy (for example, see Non-Patent Document 1), a laminated structure using a perpendicular magnetization film (for example, see Non-Patent Document 2), and the like. Proposed. These are magnetic field writing methods that basically reverse the magnetization direction of the magnetic layer using a magnetic field generated by an electric current. As a matter of course, the magnetic field generated by the current can generate a large magnetic field if the current is large, but the current that can be passed through the wiring is limited as the miniaturization progresses. By using a yoke structure that reduces the distance between the wiring and the magnetic layer or concentrates the generated magnetic field, the current value required to invert the magnetic material can be reduced. Since the magnetic field required for magnetization reversal increases, it is very difficult to achieve both low current and miniaturization. The reason why the magnetic field necessary for the magnetization reversal of the magnetic material increases due to the miniaturization is that it requires magnetic energy to overcome the thermal disturbance. The magnetic energy can be increased by increasing the magnetic anisotropy energy density and the volume of the magnetic material, but the volume is reduced by miniaturization, so it is necessary to use the shape magnetic anisotropy energy and the magnetocrystalline anisotropy energy. It is common. However, as described above, an increase in the magnetic energy of the magnetic material increases the reversal magnetic field, so it is very difficult to achieve both low current and miniaturization. Patent Document 1 proposes a fully closed magnetic circuit type yoke structure in which a perpendicularly magnetized film having a large magnetocrystalline anisotropy energy is introduced and has an extremely large current magnetic field generation efficiency. Since it becomes larger than the magnetic element, the cell area becomes relatively large, and miniaturization, reduction in current, and reduction in cell area cannot all be satisfied.

  In recent years, magnetization reversal due to spin-polarized current is theoretically expected and has been confirmed by experiments, and magnetic random access memories using spin-polarized current have been proposed (for example, see Non-Patent Document 3). . According to this method, the magnetization reversal of the magnetic material can be realized only by passing a spin-polarized current through the magnetic material, and if the volume of the magnetic material is small, the number of spin-polarized electrons to be injected is small. It is expected to be compatible. Further, since the magnetic field generated by the current is not used, a yoke structure for increasing the magnetic field is not necessary, and the cell area can be reduced. However, as a matter of course, even in the magnetization reversal method using the spin-polarized current, the problem of thermal disturbance becomes obvious as the size is reduced. As described above, in order to ensure thermal disturbance resistance, it is necessary to increase the magnetic anisotropic energy density. In the in-plane magnetization type configuration mainly studied so far, it is common to use shape magnetic anisotropy. In this case, since the magnetic anisotropy is ensured by using the shape, the reversal current becomes sensitive to the shape, and there is a problem that the variation in reversal current increases with miniaturization. Since the aspect of the MTJ cell needs to be at least 1.5 or more, the cell size also increases. When using magnetocrystalline anisotropy instead of shape magnetic anisotropy in the in-plane magnetization configuration, a material having a large magnetocrystalline anisotropy energy density (for example, Co-- When the Cr alloy material is used, the crystal axes are greatly dispersed in the plane, so that MR (Magneto Resistive) is reduced and incoherent precession is induced, resulting in an increase in reversal current.

  As described above, there are some reports on the perpendicular magnetization type MTJ configuration, but no specific means for constructing a large-scale array by a write method using a spin-polarized current has been proposed.

  As described above, it is desirable that the conventional magnetic random access memory satisfy both the reduction of the write current, the resistance to thermal disturbance of the bit information, and the reduction of the cell area at the same time. However, in the write method using the magnetic field generated by the current, It is very difficult. In addition, even with a conventional writing method using a spin-polarized current, no specific means for securing thermal disturbance resistance, which becomes apparent with miniaturization, has been proposed.

JP 2005-19464 A

Ikeda et al., “GMR and TMR films using GdFe alloy perpendicular magnetization film”, Journal of Japan Society of Applied Magnetics, Vol.24, No.4-2, 2000, p.563-566 N.Nisimura, et al., "Magnetic tunnel junction device with perpendicular magnetization films for high-density magnetic random access memory", JOURNAL OF APPLIED PHYSICS, VOLUME 91, NUMBER 8, 15 APRIL 2002 J.C. Slonczewski et al., "Current-driven excitation of magnetic multilayers", JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, VOLUME 159, NUMBER 1-2, L1-7 1996 K. Yagami et al., “Low-current spin-transfer switching and its thermal durability in a low-saturation-magnetization nanomagnet”, APPLIED PHYSICS LETTERS, VOLUME 85, NUMBER 23, 5634-5636 2004

  The present invention provides a magnetoresistive effect element, a magnetic random access memory, an electronic card and an electronic device using the same, which can maintain a high thermal disturbance resistance of bit information even when the memory cell is miniaturized and can realize a large capacity. .

  A magnetoresistive effect element according to a first aspect of the present invention is a magnetoresistive effect element in which information is recorded by flowing spin-polarized electrons through a magnetic material, and includes a magnetic material and is perpendicular to the film surface. A first pinned layer having a first magnetization directed toward the surface and a magnetic material, having a second magnetization oriented in a direction perpendicular to the film surface, and the second magnetization by the action of the spin-polarized electrons A recording layer that can be reversed, a first surface that is provided between the first fixed layer and the recording layer, and that faces the first fixed layer and a second surface that faces the recording layer. A first nonmagnetic layer having a surface, and provided between the first surface of the first nonmagnetic layer and the first fixed layer, and one or more of Fe, Co, and Ni Provided between the first magnetic metal layer containing the element, the second surface of the first nonmagnetic layer, and the recording layer; Fe, C , And a second magnetic metal layer containing at least one element and Ni. The first nonmagnetic layer includes MgO having a (001) plane orientation, and at least one of the first and second magnetic metal layers has a bcc structure and has a (001) plane orientation, Co, A magnetic material selected from Fe, Co—Fe alloy, and Fe—Ni alloy, wherein the recording layer and the second magnetic metal layer are exchange-coupled to each other, and the damping constant of the second magnetic metal layer is It is smaller than the damping constant of the recording layer.

  At least one of the first fixed layer and the recording layer includes (1) Co and at least one of Cr, Ta, Nb, V, W, Hf, Ti, Zr, Pt, Pd, Fe, and Ni. Or (2) a first layer containing at least one of Fe, Co, and Ni, and Cr, Pt, Pd, Ir, Rh, Ru, Os, Re, Au, Cu And second layers including at least one of the layers are alternately stacked.

  A magnetic random access memory according to a second aspect of the present invention includes the magnetoresistive effect element according to the first aspect and a write wiring for supplying a current to the magnetoresistive effect element.

  A magnetic random access memory according to a third aspect of the present invention covers the magnetoresistive effect element according to the first aspect, a write wiring for supplying a current to the magnetoresistive effect element, and at least a part of the write wiring, A soft magnetic film that absorbs a magnetic field leaked from the magnetoresistive element.

  A magnetic random access memory according to a fourth aspect of the present invention includes a magnetoresistive effect element according to the first aspect, a write wiring for supplying a current to the magnetoresistive effect element, and the magnetoresistive effect element sandwiched from the thickness direction. And a first soft magnetic film and a second soft magnetic film for absorbing a magnetic field leaking from the magnetoresistive effect element.

  An electronic card according to a fifth aspect of the present invention is a semiconductor chip having the magnetoresistive effect element according to the first aspect, a card portion having a window for housing the semiconductor chip and exposing the semiconductor chip, and the window And a shutter provided with a material having a magnetic shielding effect, and a terminal provided on the card unit and electrically connecting the semiconductor chip to the outside of the card unit.

  An electronic device according to a sixth aspect of the present invention is a storage unit that stores the electronic card according to the fifth aspect, and is provided in the storage unit, electrically connected to the electronic card, and data rewriting of the electronic card And a terminal for supplying a control signal.

  A manufacturing method of a magnetoresistive effect element according to a seventh aspect of the present invention is a manufacturing method of a magnetoresistive effect element in which information is recorded by flowing spin-polarized electrons through a magnetic material, comprising a magnetic material, and a film A first pinned layer having a first magnetization oriented in a direction perpendicular to the plane; and a magnetic material, having a second magnetization oriented in a direction perpendicular to the film plane, and the action of the spin-polarized electrons The recording layer capable of reversing the direction of the second magnetization, the first surface facing the first fixed layer, and the recording layer provided between the first fixed layer and the recording layer A first nonmagnetic layer having a second surface opposite to the first nonmagnetic layer; and between the first surface of the first nonmagnetic layer and the first fixed layer, Fe, Co, Ni Between the first magnetic metal layer containing one or more elements and the second surface of the first nonmagnetic layer and the recording layer A laminated structure including a second magnetic metal layer that is exchange-coupled to the recording layer and has a damping constant smaller than that of the recording layer and includes one or more elements of Fe, Co, and Ni A Co, Fe, Co—Fe alloy having a bcc structure and a (001) plane oriented, wherein the first nonmagnetic layer is formed of MgO having a (001) plane orientation. , A magnetic material selected from an Fe—Ni alloy, forming at least one of the first and second magnetic metal layers, a first layer containing at least one of Fe, Co, and Ni, Cr, Pt, At least one of the first fixed layer and the recording layer is formed by alternately laminating a second layer containing at least one of Pd, Ir, Rh, Ru, Os, Re, Au, and Cu. To do.

  According to an eighth aspect of the present invention, there is provided a method of manufacturing a magnetic random access memory, wherein the magnetoresistive effect element according to the seventh aspect is formed and a write wiring for supplying a current to the magnetoresistive effect element is formed.

  According to a ninth aspect of the present invention, there is provided a method for manufacturing a magnetic random access memory, comprising: forming a magnetoresistive effect element according to the seventh aspect; forming a write wiring for supplying a current to the magnetoresistive effect element; A soft magnetic film that covers at least a portion and absorbs the magnetic field leaked from the magnetoresistive element is formed.

  According to a tenth aspect of the present invention, there is provided a method for manufacturing a magnetic random access memory, comprising: forming a magnetoresistive effect element according to the seventh aspect; forming a write wiring for supplying a current to the magnetoresistive effect element; First and second soft magnetic films are formed to sandwich the element from the thickness direction and absorb a magnetic field leaked from the magnetoresistive element.

  According to the present invention, there are provided a magnetoresistive effect element, a magnetic random access memory, an electronic card and an electronic device using the magnetoresistive effect element which can maintain a high thermal disturbance resistance of bit information even when the memory cell is miniaturized and can realize a large capacity. Can be provided.

1 is a schematic diagram showing an MTJ element having a single pin structure according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a specific example 1-1 of an MTJ element according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a specific example 1-2 of an MTJ element according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a specific example 1-5 of an MTJ element according to an embodiment of the invention. FIG. 6 is a schematic cross-sectional view showing another example of Specific Example 1-5 of the MTJ element according to the embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing another example of Specific Example 1-5 of the MTJ element according to the embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a specific example 1-6 of the MTJ element according to the embodiment of the invention. FIG. 8 is a schematic cross-sectional view showing a specific example 1-7 of the MTJ element according to the embodiment of the invention. Schematic which shows the MTJ element of the dual pin structure 1 which concerns on one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing a specific example 2-1 of an MTJ element according to an embodiment of the present invention. Schematic which shows the MTJ element of the dual pin structure 2 which concerns on one Embodiment of this invention. FIG. 5 is a schematic cross-sectional view showing a specific example 3 of the MTJ element according to the embodiment of the invention. The figure which shows the relationship (dumping constant = 0.01) of the film thickness of a recording layer, saturation magnetization, and magnetic anisotropy energy density which concerns on one Embodiment of this invention. The figure which shows the relationship (dumping constant = 0.002) of the film thickness of a recording layer, saturation magnetization, and magnetic anisotropy energy density which concerns on one Embodiment of this invention. The figure which shows the relationship between the damping constant which concerns on one Embodiment of this invention, saturation magnetization, and a magnetic anisotropic energy density. The schematic diagram which shows the form with which the material with a small damping constant based on one Embodiment of this invention and the material with a large damping constant were disperse | distributed. 1 is a schematic sectional view showing a magnetic random access memory according to a first embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a magnetic random access memory according to a second embodiment of the present invention. The block diagram which shows the application example 1 by which the magnetic random access memory which concerns on one Embodiment of this invention was applied to the modem. The block diagram which shows the application example 2 with which the magnetic random access memory which concerns on one Embodiment of this invention was applied to the mobile telephone terminal. The top view which shows the example 3 of application with which the magnetic random access memory which concerns on embodiment of this invention was applied to the MRAM card | curd which accommodates a media content. FIG. 22 is a plan view showing a card insertion type data transfer device for transferring data to the MRAM card of FIG. 21; FIG. 22 is a cross-sectional view showing a card insertion type data transfer device for transferring data to the MRAM card of FIG. 21; FIG. 22 is a cross-sectional view showing a fitting type data transfer device for transferring data to the MRAM card of FIG. 21; FIG. 22 is a sectional view showing a slide type data transfer device for transferring data to the MRAM card of FIG. 21;

  Embodiments of the present invention will be described below with reference to the drawings. In the description, common parts are denoted by common reference symbols throughout the drawings.

[1] MTJ Element In the example of the present invention, an MTJ (Magnetic Tunnel Junction) element is used as the magnetoresistive effect element.

[1-1] Single Pin Structure FIGS. 1A and 1B are schematic views of an MTJ element having a single pin structure according to an embodiment of the present invention. Hereinafter, an MTJ element having a single pin structure according to an embodiment of the present invention will be described.

  As shown in FIGS. 1A and 1B, an MTJ element 10 includes a recording layer (free layer, free layer) 11 made of a magnetic layer, and a fixed layer (fixed magnetic layer, pinned layer) 12 made of a magnetic layer. And a non-magnetic layer 13 sandwiched between the recording layer 11 and the fixed layer 12. In the so-called perpendicular magnetization type MTJ element 10, the magnetization direction 21 of the recording layer 11 and the magnetization direction 22 of the fixed layer 12 are perpendicular to the film surface.

The MTJ element 10 has a TMR (Tunneling Magneto Resistive) effect when the nonmagnetic layer 13 is an insulator, and has a GMR (Giant Magneto Resistive) effect when the nonmagnetic layer 13 is a metal. Here, when the nonmagnetic layer 13 is an insulator, MgO (magnesium oxide), AlO (aluminum oxide, for example, Al ₂ O ₃ ) or the like is used, and when the nonmagnetic layer 13 is a metal, Cu, Pt, Au, or the like. Is used.

(Operation)
In the perpendicular magnetization type MTJ element 10, the magnetization arrangement state of the two magnetic layers (the recording layer 11 and the fixed layer 12) is a parallel arrangement (FIG. 1A) or an antiparallel arrangement (FIG. 1B). . Information of “0” and “1” is associated with the resistance value that changes depending on the magnetization arrangement state. Further, information is written by passing a spin-polarized current 30 through the MTJ element 10 and changing the magnetization direction 21 of the recording layer 11. However, spin-polarized electrons (hereinafter referred to as spin-polarized electrons) flow in the opposite direction to the spin-polarized current 30.

  Specifically, as shown in FIG. 1A, when a spin-polarized current 30 is passed from the recording layer 11 to the fixed layer 12, spin-polarized electrons are injected from the fixed layer 12 to the recording layer 11, and the fixed layer The magnetization direction 22 of 12 and the magnetization direction 21 of the recording layer 11 are arranged in parallel. On the other hand, as shown in FIG. 1B, when a spin-polarized current 30 is passed from the fixed layer 12 to the recording layer 11, the spin-polarized electrons flow from the recording layer 11 to the fixed layer 12 and are parallel to the fixed layer 12. Electrons having spins are transmitted and electrons having antiparallel spins are reflected. As a result, the magnetization direction 21 of the recording layer 11 and the magnetization direction 22 of the fixed layer 12 are antiparallel.

(Magnetic material)
In the MTJ element 10, a high-performance MTJ element 10 can be realized by using a magnetic layer having a large reversal current as the fixed layer 12 and using a magnetic layer having a reversal current smaller than that of the fixed layer 12 as the recording layer 11. . When the magnetization reversal is caused by the spin-polarized current 30, the reversal current is proportional to the saturation magnetization, the anisotropic magnetic field, and the volume. Therefore, these are adjusted appropriately to obtain a difference between the reversal currents of the recording layer 11 and the fixed layer 12. You can turn on.

As the magnetic material constituting the recording layer 11 and the fixed layer 12 realizing the perpendicular magnetization, a material having a high magnetocrystalline anisotropy energy density of, for example, 5 × 10 ⁵ erg / cc or more is desirable, and specific examples are given below. .

(1) Irregular alloy An alloy containing Co as a main component and containing one or more elements of Cr, Ta, Nb, V, W, Hf, Ti, Zr, Pt, Pd, Fe, and Ni. Examples thereof include a CoCr alloy, a CoPt alloy, a CoCrTa alloy, a CoCrPt alloy, a CoCrPtTa alloy, and a CoCrNb alloy. These alloys can adjust the magnetic anisotropy energy density and saturation magnetization by increasing the proportion of nonmagnetic elements.

(2) ordered alloy Fe, Co, one or more elements and Pt of Ni, an alloy consisting of at least one element of Pd, the crystal structure of the alloy L1 ₀ type ordered alloy. For _{example, Fe 50 Pt 50, Fe 50} Pd 50, Co 50 Pt 50, Fe 30 Ni 20 Pt 50, Co 30 Fe 20 Pt 50, Co 30 Ni 20 Pt 50 , and the like. These ordered alloys are not limited to the above composition ratio. By adding an impurity element such as Cu (copper), Cr, Ag (silver), an alloy thereof, or an insulator to these ordered alloys, the magnetic anisotropy energy density and saturation magnetization can be adjusted low.

(3) Artificial lattice Any one of Fe, Co, Ni, an alloy containing one or more elements, and Cr, Pt, Pd, Ir, Rh, Ru, Os, Re, Au, Cu A structure in which one element or an alloy containing one or more elements is alternately laminated. Examples thereof include a Co / Pt artificial lattice, a Co / Pd artificial lattice, a CoCr / Pt artificial lattice, a Co / Ru artificial lattice, Co / Os, Co / Au, and a Ni / Cu artificial lattice. These artificial lattices can adjust the magnetic anisotropy energy density and saturation magnetization by adjusting the addition of elements to the magnetic layer and the film thickness ratio of the magnetic layer and the nonmagnetic layer.

(4) Ferrimagnetic material A ferrimagnetic material comprising an alloy of a rare earth metal and a transition metal. For example, an amorphous alloy composed of Tb (terbium), Dy (dysprosium), Gd (gadolinium), and one or more elements of transition metals. For example, TbFe, TbCo, TbFeCo, DyTbFeCo, GdTbCo and the like can be mentioned. These alloys can adjust magnetic anisotropy energy density and saturation magnetization by adjusting the composition.

The magnetic layer may have a structure in which the magnetic part and the non-magnetic part are separated by segregation of the non-magnetic part. For example, oxides, nitrides, and carbides such as SiO ₂ , MgO, SiN, and SiC may be used as the non-magnetic part, or an alloy such as a non-magnetic CoCr alloy having a high Cr concentration of 25 at% or more may be used.

  Further, at the interface of the magnetic layers (recording layer 11 and fixed layer 12) in contact with the nonmagnetic layer 13 of the MTJ element 10, one or more elements of Fe, Co, Ni, or one of these as high polarizability materials are used. A configuration in which a magnetic metal layer made of an alloy containing an element is arranged to increase the magnetoresistive (MR) ratio may be used. However, since these magnetic layers usually have in-plane magnetization in a single layer, it is necessary to adjust the magnetic film thickness ratio with the perpendicular magnetic anisotropic material to be laminated so as not to impair the stability of perpendicular magnetization. is there.

  In addition, the recording layer 11 and the fixed layer 12 may have a structure in which magnetic layers are stacked, and one of the magnetic layers may have a so-called granular structure in which a magnetic material is dispersed.

(effect)
In the MTJ element 10 having a single pin structure according to an embodiment of the present invention, in order to orient the magnetization directions 21 and 22 of the recording layer 11 and the fixed layer 12 in the direction perpendicular to the film surface, perpendicular magnetic anisotropy is necessary. It becomes. When this magnetic anisotropy is reliant on the magnetocrystalline anisotropy, it does not depend on the shape, and therefore the anisotropic magnetic field due to the shape anisotropy does not change in principle even if the pattern size of the magnetic film is reduced. Therefore, miniaturization is possible only when the magnetic film is a perpendicular magnetization film without increasing the reversal current density.

  Further, as described above, since the reversal current density does not increase even if the MTJ element 10 is miniaturized, a fine MTJ element 10 of 90 nm or less that cannot be realized by a conventional magnetic random access memory (MRAM). A large-capacity (for example, 256 Mbit or more) magnetic random access memory can be realized.

  A specific example of the MTJ element 10 having a single pin structure will be described below.

(A) Specific example 1-1
In the MTJ element 10 of Specific Example 1-1, the recording layer 11 is made of an artificial lattice, and the fixed layer 12 is made of an ordered alloy.

  FIG. 2 is a schematic cross-sectional view of Example 1-1 of the MTJ element according to one embodiment of the present invention. A specific example 1-1 of the MTJ element 10 will be described below.

  As shown in FIG. 2, the MTJ element 10 has a structure in which a crystal orientation base 15, a fixed layer 12, a tunnel barrier layer TB (nonmagnetic layer 13), a recording layer 11, and a cap layer 16 are laminated in this order. A lower electrode 14 is provided on the bottom surface of the crystal orientation substrate 15, and an upper electrode 17 is provided on the upper surface of the cap layer 16.

  Here, the fixed layer 12 only needs to have a larger current for magnetization reversal than the recording layer 11, and may adjust the saturation magnetization, the anisotropic magnetic field, and the film thickness as described above. For example, when an FePt or CoPt ordered alloy is used as the fixed layer 12, it is necessary to orient the (001) plane of the fct (face centered tetragonal) structure in order to develop perpendicular magnetic anisotropy. For this purpose, an ultrathin substrate made of MgO (magnesium oxide) of about several nm may be used as the crystal orientation substrate 15. In addition, the fcc (face centered cubic) structure and the bcc (body centered cubic) structure having a lattice constant of about 2.8Å, 4Å, and 5.6Å are used as the base 15 for crystal orientation. An element or a compound having, for example, Pt, Pd, Ag, Au, Al, Cr, or an alloy containing them as a main component can be used.

  The recording layer 11 must have a smaller current for magnetization reversal than the fixed layer 12. As described above, the saturation magnetization, the anisotropic magnetic field, and the film thickness may be adjusted so that the current is smaller than that of the fixed layer 12. For example, when a Co / Pt artificial lattice is used, the coercive force can be adjusted by adjusting the film thicknesses of Co and Pt.

Therefore, the stacked configuration of the specific example 1-1 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Pt having a thickness of 3 nm formed on MgO having a thickness of 0.5 nm. Here, the (001) plane of the MgO / Pt laminated film is oriented. The fixed layer 12 is made of Fe ₅₀ Pt ₅₀ having a (001) plane oriented with a thickness of 10 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.5 nm. The recording layer 11 is composed of a laminated film [Co / Pt] 5 in which five cycles of Co having a thickness of 0.45 nm and Pt having a thickness of 1.5 nm are stacked as one cycle. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  In such an MTJ element 10 according to Example 1-1, when coercivity and saturation magnetization are measured with a vibrating sample magnetometer, the fixed layer 12 is 5 kOe, 700 emu / cc, and the recording layer 11 is 130 Oe, 340 emu / cc. is there.

A Pt layer may be inserted at the Co interface between the tunnel barrier layer TB and the recording layer 11 to the extent that the MR ratio is not impaired. Further, as the fixed layer 12, a Co ₅₀ Pt ₅₀ ordered layer, a Co ₃₀ Fe ₂₀ Pt ₅₀ ordered layer, or the like may be used instead of the above-described Fe ₅₀ Pt ₅₀ ordered layer. Further, as the fixed layer 12, (Fe ₅₀ Pt ₅₀ ) _88- (SiO ₂ ) ₁₂ or the like having a structure in which these are divided by SiO ₂ , MgO, or the like may be used. As the recording layer 11, a Co / Pd artificial lattice may be used instead of the Co / Pt artificial lattice. Al-O may be used as the tunnel barrier layer TB.

The order of stacking the recording layer 11 and the fixed layer 12 may be reversed. In this case, the MTJ element 10 has the following laminated structure. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Pt having a thickness of 3 nm formed on MgO having a thickness of 0.5 nm. The recording layer 11 is composed of a [Co / Pt] 4 / Co artificial lattice in which five cycles are formed with Co having a thickness of 0.3 nm and Pt having a thickness of 1.5 nm as one cycle. The artificial lattice has Pt oriented in the (001) plane by the crystal orientation substrate 15. The tunnel barrier layer TB is made of MgO having a thickness of 1.5 nm, and is oriented in the (001) plane, reflecting the orientation of the artificial lattice that is the recording layer 11. The fixed layer 12 is made of Fe ₅₀ Pt ₅₀ having a film thickness of 10 nm, and the Fe ₅₀ Pt ₅₀ (001) plane is oriented to reflect the MgO (001) plane. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm. Even in such a stacking order, the coercive force and saturation magnetization of the recording layer 11 and the fixed layer 12 show the same values as described above. In the case of this stacking order, since Fe ₅₀ Pt ₅₀ is used as the fixed layer 12, the tunnel barrier layer TB is particularly preferably MgO with the (001) plane oriented. The artificial lattice [Co / Pt] 4 / Co that is the recording layer 11 is not necessarily oriented in the (001) plane, and may be oriented in the (111) plane. In this case, for example, by forming the crystal orientation base 15 made of Pt having a thickness of 5 nm on the lower electrode 14 made of Ta having a thickness of 10 nm, the (111) plane of Pt is oriented. In order to orient the MgO of the tunnel barrier layer TB on the recording layer 11 to the (001) plane, the film thickness of Co on the interface side of the tunnel barrier layer TB of the artificial lattice [Co / Pt] 4 / Co that is the recording layer 11 is increased. May be Co ₆₀ Fe ₂₀ B ₂₀ having a thickness of 0.5 nm and an artificial lattice [Co / Pt] 4 / Co ₆₀ Fe ₂₀ B ₂₀ .

  In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

(B) Specific example 1-2
The MTJ element 10 of Specific Example 1-2 is a modification of Specific Example 1-1, and a high polarizability layer is provided at the interface between the tunnel barrier layer TB and the recording layer 11 and at the interface between the tunnel barrier layer TB and the fixed layer 12. Provided.

  FIG. 3 is a schematic cross-sectional view of a specific example 1-2 of the MTJ element according to the embodiment of the invention. Specific examples 1-2 of the MTJ element 10 will be described below.

  As shown in FIG. 3, in the MTJ element 10 of Example 1-2, the first high polarizability layer 18 is provided at the interface between the fixed layer 12 and the tunnel barrier layer TB, and the recording layer 11 and the tunnel barrier layer TB are provided. The second high polarizability layer 19 is provided at the interface between the first and second layers. The first high polarizability layer 18 is exchange coupled with the fixed layer 12, and the second high polarizability layer 19 is exchange coupled with the recording layer 11. The film thickness of the second high polarizability layer 19 is desirably smaller than the film thickness of the first high polarizability layer 18. This is because the recording layer 11 is inverted at a current density smaller than that of the fixed layer 12, and the magnetic film thickness represented by the product of the volume of the recording layer 11 and the saturation magnetization Ms is set to the magnetic layer of the fixed layer 12. Make it smaller than the film thickness. Therefore, it is desirable to reduce the saturation magnetization Ms, reduce the thickness of the film, or reduce the anisotropic energy density.

  The first and second high polarizability layers 18 and 19 are made of, for example, a magnetic metal layer containing one or more elements of Fe, Co, and Ni. In addition, at least one of the first and second high polarizabilities 18, 19 includes at least one element of Fe, Co, and Ni and one or more elements of B, Nb, Zr, Ta, V, and W. The crystal structure of the ferromagnetic alloy may be a bcc structure.

The stacked structure of Example 1-2 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Pt having a thickness of 3 nm formed on MgO having a thickness of 0.5 nm. Here, the (001) plane of the MgO / Pt laminated film is oriented. The fixed layer 12 is made of Co ₅₀ Pt ₅₀ with a (001) plane oriented with a thickness of 15 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.5 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.5 nm. The second high polarizability layer is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.0 nm. The recording layer 11 is composed of a laminated film [Pd / Co] 4 in which Pd having a film thickness of 0.7 nm and Co having a film thickness of 0.3 nm are laminated in four periods. The cap layer 16 is made of Pd having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  In the MTJ element 10 according to the specific example 1-2, when the coercive force and the saturation magnetization are measured with a dynamic sample magnetometer, the fixed layer 12 is 3.5 kOe and 750 emu / cc, and the recording layer 11 is 250 Oe and 500 emu / cc. cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the first high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body. Due to the contribution of the high polarizability layers 18 and 19, the magnetoresistance ratio of the MTJ element 10 is 120%.

Note that (Co ₅₀ Pt ₅₀ ) _90- (MgO) ₁₀ or the like having a structure in which the fixed layer 12 is divided by SiO ₂ , MgO, or the like may be used. As the recording layer 11, a CoCr / Pd artificial lattice may be used instead of the Co / Pd artificial lattice. Al-O may be used as the tunnel barrier layer TB. The order of stacking the recording layer 11 and the fixed layer 12 may be reversed. In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc., which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, and Ir can be used. .

(C) Specific Example 1-3
The MTJ element 10 of Specific Example 1-3 is the same as the stack of Specific Example 1-2 shown in FIG. 3, and is high at the interface between the tunnel barrier layer TB and the recording layer 11 and at the interface between the tunnel barrier layer TB and the fixed layer 12. Each of the polarizability layers is provided. The high polarization layer, Co in which the bcc structure (001) plane are stacked and oriented, Fe, Co-Fe alloy, consists Fe-Ni alloy, and (001) plane of L1 ₀ type oriented Ordered alloys are laminated. This L10 type ordered alloy may be a recording layer or a fixed layer.

The stacked structure of Specific Example 1-3 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Pt having a thickness of 3 nm formed on MgO having a thickness of 0.5 nm. Here, the (001) plane of the MgO / Pt laminated film is oriented. The fixed layer 12 is made of Fe ₅₀ Pt ₅₀ having a (001) plane oriented with a thickness of 15 nm. The first high polarizability layer 18 is made of Fe having a thickness of 1.0 nm. Fe is oriented in the (001) plane of the bcc structure. The tunnel barrier layer TB is made of MgO having a (001) plane with a thickness of 1.5 nm. The second high polarizability layer is made of Co ₅₀ Fe ₅₀ having a thickness of 0.5 nm. Co ₅₀ Fe ₅₀ has the (001) plane of the bcc structure oriented. The recording layer 11 is composed of a stacked film [Pd / Co] 4 in which Pd having a film thickness of 0.7 nm and Co having a film thickness of 0.3 nm are stacked for four periods. The cap layer 16 is made of Pd having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  In the MTJ element 10 according to Specific Example 1-3, when coercivity and saturation magnetization are measured with a vibrating sample magnetometer, the fixed layer 12 is 4.5 kOe, 800 emu / cc, and the recording layer 11 is 200 Oe, 550 emu / cc. cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the first high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body. Due to the contribution of the high polarizability layers 18 and 19, the magnetoresistance ratio of the MTJ element 10 is 120%.

(D) Specific example 1-4
The MTJ element 10 of Specific Example 1-4 is the same as the stack of Specific Example 1-2 shown in FIG. 3, and is high at the interface between the tunnel barrier layer TB and the recording layer 11 and at the interface between the tunnel barrier layer TB and the fixed layer 12. Each of the polarizability layers is provided. At least one of the recording layer 11 and the fixed layer 12 is made of a RE-TM amorphous alloy having a rare earth metal (RE) and a transition metal (TM).

The laminated structure of Specific Example 1-4 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Ru having a thickness of 5 nm. The fixed layer 12 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) ₁₅ having a (002) plane oriented with a thickness of 30 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 2.0 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.0 nm. The second high polarizability layer 19 is made of Co ₆₀ Fe ₂₀ B ₂₀ having a thickness of 1.0 nm. The recording layer 11 is made of Tb ₂₇ (Fe ₇₁ Co ₂₉ ) ₇₃ having a thickness of 10 nm. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  In the MTJ element 10 according to the specific example 1-4, when coercivity and saturation magnetization are measured with a vibrating sample magnetometer, the fixed layer 12 is 4.0 kOe, 500 emu / cc, the recording layer 11 is 500 Oe, 300 emu / cc. cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the first high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body. Due to the contribution of the high polarizability layers 18 and 19, the magnetoresistance ratio of the MTJ element 10 becomes 100%.

The fixed layer 12 may be Tb ₂₂ (Fe ₇₁ Co ₂₉ ) ₇₈ having a thickness of 50 nm. In this case, since the RE-TM alloy such as Tb ₂₂ (Fe ₇₁ Co ₂₉ ) ₇₈ is an amorphous alloy, Ru having a film thickness of 5 nm used as the crystal orientation base 15 is not necessarily required. However, Pt, Ru, SiN, or the like may be used as a buffer layer for smoothly forming the RE-TM alloy. The coercivity and saturation magnetization in this case were 8 kOe and 200 emu / cc as a result of measurement with a vibrating sample magnetometer. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, they behave as one magnetic layer, so the above-described coercive force and saturation magnetization are values when viewed as one magnetic body. .

  Further, a laminated ferrimagnetic structure (a structure in which magnetic layers / metal layers are alternately laminated) may be used for the fixed layer 12. Examples of the magnetic layer having a laminated ferri structure include Fe, Co, Ni, and alloys thereof, and examples of the metal layer having a laminated ferri structure include Ru, Ir, Rh, Re, and Os. Specific examples of the laminated ferri structure include Co / Ru, Co / Ir, and Co / Rh. In this case, the fixed layer 12 is composed of an artificial lattice [Ru / Co] 15 in which 15 cycles of Ru having a thickness of 0.8 nm and Co having a thickness of 0.3 nm are stacked as one cycle.

  Al-O may be used as the tunnel barrier layer TB. The order of stacking the recording layer 11 and the fixed layer 12 may be reversed. In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

(E) Specific Example 1-5
The MTJ element of Specific Example 1-5 has a Synthetic AntiFerro (SAF) structure in which two magnetic layers constituting the fixed layer 12 are exchange-coupled antiferromagnetically.

  FIG. 4 is a schematic cross-sectional view of Example 1-5 of an MTJ element according to an embodiment of the present invention. Specific examples 1-5 of the MTJ element 10 will be described below.

  As shown in FIG. 4, in the MTJ element 10 of Specific Example 1-5, the fixed layer 12 is provided between the first magnetic layer 34, the second magnetic layer 36, and the first and second magnetic layers 34, 36. The first nonmagnetic layer 35 is a SAF structure in which the first and second magnetic layers 34 and 36 are antiferromagnetically exchange coupled. In this case, since the magnetizations 22-1 and 22-2 of the first and second magnetic layers 34 and 36 are in an antiparallel state, the leakage magnetic field from the first and second magnetic layers 34 and 36 is canceled, As a result, there is an effect of reducing the leakage magnetic field of the fixed layer 12. Further, the exchange-coupled magnetic layers 34 and 36 improve thermal disturbance resistance as an effect of increasing the volume.

The laminated structure of Specific Example 1-5 of such an MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Ru having a thickness of 5 nm. The fixed layer 12 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) ₁₅ having a (002) plane of 20 nm as the first magnetic layer 34, and the first nonmagnetic layer 35 The second magnetic layer 36 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) _{15 having a} thickness of 15 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.0 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.0 nm. The recording layer 11 is composed of a laminated film [Co / Pt] 5 in which five cycles of Co having a thickness of 0.4 nm and Pt having a thickness of 0.8 nm are stacked as one cycle. Here, the first Co layer of the multilayer film [Co / Pt] 5 formed on MgO functions as the second high polarizability layer 19. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  Here, the material of the first nonmagnetic layer 35 for antiferromagnetically coupling the upper and lower magnetic layers 34 and 36 is one or more elements of Ru, Os, Re, and Rh, or an alloy containing a main component. Can be given.

  Note that antiferromagnetic coupling can also be realized when the first and second magnetic layers 34 and 36 are made of a ferrimagnetic material of RE-TM alloy. In this case, the first nonmagnetic layer 35 is not necessarily used. An example thereof will be described below with reference to FIGS. 5 (a) and 5 (b).

  The RE-TM alloy is in a state where the magnetic moment of the rare earth metal (RE) and the magnetic moment of the transition metal (TM) are antiferromagnetically coupled. It is known that when RE-TM alloys are laminated, REs and TMs are ferromagnetically coupled. Since the magnetic moments of RE and TM cancel each other, the magnetic moment of the RE-TM alloy can be adjusted by the composition.

  For example, as shown in FIG. 5A, in the case of the RE-TM alloy layer 51 in which the RE magnetic moment 41 is larger than the TM magnetic moment 42, the remaining magnetic moment 43 is in the same direction as the RE magnetic moment 41. . When the RE-TM alloy layer 52 in which the RE magnetic moment 44 is larger than the TM magnetic moment 45 is laminated on the RE-TM alloy layer 51, the RE magnetic moments 41 and 44 and the TM magnetic moment 42 are stacked. , 45 are in the same direction, and the magnetic moments 43, 46 of the two RE-TM alloy layers 51, 52 are in the same direction and are in a parallel state.

  On the other hand, when the RE-TM alloy layer 53 having a RE magnetic moment 47 smaller than the TM magnetic moment 48 is laminated on the RE-TM alloy layer 51 as shown in FIG. The magnetic moments 43 and 49 of the TM alloy layers 51 and 53 are in an antiparallel state.

For example, a Tb—Co alloy is a so-called compensation composition in which when Tb is 22 at%, the magnetic moment of Tb and the magnetic moment of Co are the same, and the magnetic moment is zero. When 10 nm Tb ₂₅ Co ₇₅ and 10 nm Tb ₂₀ Co ₈₀ are stacked, their magnetic moments are antiparallel.

Using such a form, the MTJ element 10 in which the two magnetic layers forming the fixed layer 12 are coupled in antiparallel can be manufactured. Specifically, the fixed layer 12 of FIG. 4 may be configured by laminating two layers of the first and second magnetic layers 34 and 36 made of RE-TM alloy. For example, the first magnetic layer 34 is made of Tb ₂₂ (Fe ₇₁ Co ₂₉ ) ₇₈ having a thickness of 20 nm, and the second magnetic layer 36 is made of Tb ₂₆ (Fe ₇₁ Co ₂₉ ) ₇₄ having a thickness of 15 nm. Here, Tb ₂₄ (Fe ₇₁ Co ₂₉ ) ₇₆ is the compensation composition.

  Further, when the first and second magnetic layers 34 and 36 are made of a RE-TM alloy, the first nonmagnetic layer 35 is provided between the first and second magnetic layers 34 and 36 to provide antiferromagnetic coupling. Can also be realized. An example of this will be described below with reference to FIGS. 6 (a) and 6 (b).

  The TM magnetic moments 42 and 45 of the first and second magnetic layers 51 and 52 shown in FIG. 6A are considered to be exchange coupled via the nonmagnetic layer 54. Similarly, the TM magnetic moments 42 and 48 of the first and second magnetic layers 51 and 53 shown in FIG. 6B are considered to be exchange coupled via the nonmagnetic layer 54.

  For example, as shown in FIG. 6A, when a metal that couples Co antiferromagnetically and its alloy are used as the nonmagnetic layer 54, the RE magnetic moment 41 of the RE-TM alloy layer 51 is expressed as TM. The RE magnetic moment 44 of the RE-TM alloy layer 52 is set larger than the TM magnetic moment 45. That is, when the nonmagnetic layer 54 contributes to the antiferromagnetic coupling, the magnitude relationship between the TM magnetic moment 42 and the RE magnetic moment 41 and the magnitude relation between the TM magnetic moment 45 and the RE magnetic moment 44 should be set to be the same. For example, the magnetic moments of TM and RE cancel each other, and the magnetic moments 43 and 46 become antiparallel in the first and second magnetic layers 51 and 52. Examples of the material of the nonmagnetic layer 54 that antiferromagnetically couples Co include one or more elements of Ru, Rh, Os, and Re, or an alloy containing the element as a main component.

  In addition, as shown in FIG. 6B, when the metal that ferromagnetically couples Co and its alloy are used as the nonmagnetic layer 54, the RE magnetic moment 41 of the RE-TM alloy layer 51 is set to TM. The magnetic moment is made larger than the magnetic moment, and the RE magnetic moment 47 of the RE-TM alloy layer 53 is made smaller than the TM magnetic moment. That is, when the nonmagnetic layer 54 contributes to the ferromagnetic coupling, the magnitude relationship between the TM magnetic moment 42 and the RE magnetic moment 41 and the magnitude relationship between the TM magnetic moment 48 and the RE magnetic moment 47 are reversed. , TM and RE magnetic moments cancel each other, and the magnetic moments 43 and 49 become antiparallel in the first and second magnetic layers 51 and 53. Examples of the material of the nonmagnetic layer 54 that ferromagnetically couples Co include one or more elements of Pt, Pd, or the like, or an alloy containing the element as a main component.

  By utilizing such a form, the first magnetic layer 51, the nonmagnetic layer 54, and the second magnetic layers 52 and 53 shown in FIGS. 6A and 6B are used as the first layer of the fixed layer 12 shown in FIG. The magnetic layer 34, the nonmagnetic layer 35, and the second magnetic layer 36 may be made to correspond to each other.

  In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

  In addition, a RE-TM alloy in which the magnetic moment of RE is larger than the magnetic moment of TM, and a metal or alloy mainly composed of a transition metal may be laminated.

(F) Specific Example 1-6
In the MTJ element of Specific Example 1-6, the recording layer 11 is made of an artificial lattice having a SAF structure.

  FIG. 7 is a schematic cross-sectional view of Example 1-6 of an MTJ element according to an embodiment of the present invention. Specific examples 1-6 of the MTJ element 10 will be described below.

  As shown in FIG. 7, in the MTJ element 10 of Specific Example 1-6, the recording layer 11 is composed of the first magnetic layer 31, the first nonmagnetic layer 32, and the second magnetic layer 33. The SAF structure in which the second magnetic layers 31 and 33 are exchange-coupled antiferromagnetically. In this case, since the magnetizations 21-1 and 21-2 of the first and second magnetic layers 31 and 33 are in an antiparallel state, the leakage magnetic fields from the first and second magnetic layers 31 and 33 are offset, As a result, there is an effect of reducing the leakage magnetic field of the recording layer 11. Further, the exchange-coupled magnetic layers 31 and 33 improve thermal disturbance resistance as an effect of increasing the volume.

The laminated structure of Specific Example 1-5 of such an MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation base 15 is made of 3 nm thick Pt formed on 0.5 nm thick MgO. Here, the (001) plane of the MgO / Pt laminated film is oriented. The fixed layer 12 is made of Co ₅₀ Pt ₅₀ with a (001) plane oriented with a thickness of 20 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.5 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.2 nm. The second high polarizability layer 19 is made of Co ₆₃ Fe ₁₇ B ₁₀ having a thickness of 0.8 nm. The first magnetic layer 31 of the recording layer 11 is composed of an artificial lattice [Pd / Co] 4 in which Pd having a film thickness of 0.7 nm and Co having a film thickness of 0.3 nm are stacked for four periods. The first nonmagnetic layer 32 of the recording layer 11 is made of Ru having a thickness of 0.9 nm. The second magnetic layer 33 of the recording layer 11 is composed of an artificial lattice [Co / Pd] 3 in which three cycles are laminated with Co having a thickness of 0.3 nm and Pd having a thickness of 0.7 nm as one cycle. The cap layer 16 is made of Pd having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

  In addition, the first and second magnetic layers 31 and 33 may be an ordered alloy or an irregular alloy instead of an artificial lattice. A RE-TM alloy in which the magnetic moment of RE is larger than the magnetic moment of TM, a metal having a transition metal as a main component, and an alloy may be laminated.

(G) Specific Example 1-7
In the MTJ element of Specific Example 1-7, both the recording layer 11 and the fixed layer 12 have the SAF structure.

  FIG. 8 is a schematic cross-sectional view of Specific Example 1-7 of an MTJ element according to an embodiment of the present invention. Specific examples 1-7 of the MTJ element 10 will be described below.

  As shown in FIG. 8, in the MTJ element 10 of Specific Example 1-7, the recording layer 11 includes the first magnetic layer 31, the first nonmagnetic layer 32, and the second magnetic layer 33. The SAF structure in which the second magnetic layers 31 and 33 are exchange-coupled antiferromagnetically. Further, the fixed layer 12 includes a first magnetic layer 34, a first nonmagnetic layer 35, and a second magnetic layer 36, and the first and second magnetic layers 34, 36 are antiferromagnetically exchange coupled. This is the SAF structure. In this case, since the magnetizations 21-1 and 21-2 of the first and second magnetic layers 31 and 33 are in an antiparallel state, the leakage magnetic fields from the first and second magnetic layers 31 and 33 are offset, As a result, there is an effect of reducing the leakage magnetic field of the recording layer 11. Similarly, since the magnetizations 22-1 and 22-2 of the first and second magnetic layers 34 and 36 are in an antiparallel state, the leakage magnetic field from the first and second magnetic layers 34 and 36 is canceled, As a result, there is an effect of reducing the leakage magnetic field of the fixed layer 12. Further, the exchange-coupled magnetic layers 31 and 33 and the magnetic layers 34 and 36 improve heat disturbance resistance as an effect of increasing the volume.

The laminated structure of Specific Example 1-7 of such an MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Ru having a thickness of 5 nm. The pinned layer 12 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) ₁₅ having a (002) plane orientation of 20 nm as the first magnetic layer 34, and the second nonmagnetic layer 35 is made of The second magnetic layer 36 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) _{15 having a} thickness of 15 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.0 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.2 nm. The second high polarizability layer is made of Co ₆₃ Fe ₁₇ B ₁₀ having a thickness of 0.8 nm. The first magnetic layer 31 of the recording layer 11 is composed of an artificial lattice [Pd / Co] 4 in which Pd having a film thickness of 0.7 nm and Co having a film thickness of 0.3 nm are stacked for four periods. The second nonmagnetic layer 32 of the recording layer 11 is made of Ru having a thickness of 0.9 nm. The second magnetic layer 33 of the recording layer 11 is composed of an artificial lattice [Co / Pd] 3 in which three cycles of Co having a thickness of 0.3 nm and Pd having a thickness of 0.7 nm are stacked as one cycle. The cap layer 16 is made of Pd having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

  As described above, the antiparallel coupling is composed of a RE-TM alloy laminated film in which the magnitude relationship between the RE magnetic moment and the TM magnetic moment is reversed, and the RE-TM alloy in which the RE magnetic moment is greater than the TM magnetic moment. And a metal or alloy mainly composed of a transition metal may be laminated, or a so-called SAF structure with a nonmagnetic layer of Ru or the like interposed therebetween may be used.

[1-2] Dual pin structure 1
FIGS. 9A and 9B are schematic cross-sectional views of MTJ elements having a dual pin structure 1 according to an embodiment of the present invention. The dual pin structure 1 MTJ element according to an embodiment of the present invention will be described below.

  As shown in FIGS. 9A and 9B, the MTJ element 10 includes a recording layer 11 made of a magnetic layer, first and second fixed layers 12a and 12b made of a magnetic layer, a recording layer 11 and a first layer. And a first nonmagnetic layer 13a sandwiched between one fixed layer 12a and a second nonmagnetic layer 13b sandwiched between the recording layer 11 and the second fixed layer 12b. . In the so-called perpendicular magnetization type MTJ element 10, the magnetization direction 21 of the recording layer 11 and the magnetization directions 22a and 22b of the fixed layers 12a and 12b are perpendicular to the film surface. Here, the first and second pinned layers 12a and 12b have antiparallel magnetization arrangements in which the magnetizations 22a and 22b are directed in different directions.

The MTJ element 10 has a TMR effect when the first and second nonmagnetic layers 13a and 13b are insulators, and has a GMR effect when the first and second nonmagnetic layers 13a and 13b are metal. . Here, when the first and second nonmagnetic layers 13a and 13b are insulators, MgO (magnesium oxide), AlO (aluminum oxide, for example, Al ₂ O ₃ ) or the like is used, and the first and second nonmagnetic layers are used. When the magnetic layers 13a and 13b are metal, Cu, Pt, Au or the like is used.

(Operation)
In the MTJ element 10 having the dual pin structure 1, the magnetic layer (the recording layer 11 and the fixed layer 12a) that sandwiches the first nonmagnetic layer 13a or the magnetic layer (the recording layer 11 and the fixed layer) that sandwiches the second nonmagnetic layer 13b. Layer 12b) takes a parallel or antiparallel arrangement. However, when viewed as the entire MTJ element 10, in FIGS. 9A and 9B, both the parallel arrangement and the antiparallel arrangement exist at the same time, so that the overall magnetoresistance of both does not change. Accordingly, when the fixed layers 12a and 12b are provided in opposite directions on both sides of the recording layer 11 as described above, a difference is produced in the change in magnetoresistance via the first and second nonmagnetic layers 13a and 13b. It is necessary to keep.

  For example, when the first nonmagnetic layer 13a is a tunnel barrier layer TB and the second nonmagnetic layer 13b is a metal layer, the change in magnetoresistance that occurs in the tunnel barrier layer TB is greater in the magnetoresistance that occurs in the metal layer. Compared with the change, the magnetization arrangement via the first nonmagnetic layer 13a corresponds to information of “0” and “1”. Accordingly, the parallel arrangement is shown in FIG. 9A and the antiparallel arrangement is shown in FIG. 9B. The second nonmagnetic layer 13b may be a tunnel barrier layer TB, and the first nonmagnetic layer 13a may be a metal layer.

  As described above, when the first nonmagnetic layer 13a is the tunnel barrier layer TB, the magnetization arrangement state of the two magnetic layers (the recording layer 11 and the fixed layer 12a) is parallel (FIG. 9A) or anti-parallel. It becomes a parallel arrangement (FIG. 9B). Information of “0” and “1” is associated with the resistance value that changes depending on the magnetization arrangement state. Then, a spin-polarized current 30 is passed through the MTJ element 10 to change the magnetization direction 21 of the recording layer 11 and write information. However, spin-polarized electrons flow in the opposite direction to the spin-polarized current 30.

  Specifically, as shown in FIG. 9A, when a spin-polarized current 30 is passed from the second fixed layer 12b to the first fixed layer 12a, the spin-polarized electrons are transferred from the first fixed layer 12a. It flows to the second fixed layer 12b. In this case, since upward spins are mainly injected from the first fixed layer 12a, a torque that tries to align the spins of the recording layer 11 in parallel acts, and the spin polarization from the recording layer 11 to the second fixed layer 12b occurs. In the process of the polar electrons flowing, the second fixed layer 12b easily transmits downward spins, so that the reflected upward spin electrons are injected into the recording layer 11, and the magnetization direction 21 of the recording layer 11 has the first magnetization direction 21. 1 is parallel to the magnetization direction 22a of the fixed layer 12a. On the other hand, as shown in FIG. 9B, when a current is passed from the second pinned layer 12b to the first pinned layer 12a, the same can be considered, and the magnetization direction 21 of the recording layer 11 is the second pinned layer. It becomes parallel to the magnetization direction 22b of the layer 22b.

(Magnetic material)
As the magnetic material of the recording layer 11 and the fixed layers 12a and 12b, the same material as the single pin structure can be used.

(effect)
According to the MTJ element 10 having the dual pin structure 1 according to the embodiment of the present invention, the same effect as the single pin structure can be obtained. Furthermore, since the pinned layers 12a and 12b are provided with a dual pin structure on both sides of the recording layer 11, the effect of reflection of spin-polarized electrons can be used more, so that the reversal current can be further reduced as compared with the single pin structure. Can do.

  A specific example of the MTJ element 10 having the dual pin structure 1 will be described below.

(A) Specific example 2-1
In the MTJ element of Example 2-1, one of the fixed layers 12a and 12b provided on both sides of the recording layer 11 has a SAF structure.

  FIG. 10 is a schematic cross-sectional view of a specific example 2-1 of an MTJ element according to an embodiment of the present invention. A specific example 2-1 of the MTJ element 10 will be described below.

  As shown in FIG. 10, the MTJ element 10 includes a crystal orientation substrate 15, a first fixed layer 12a, a first nonmagnetic layer 13a, a recording layer 11, a first high polarizability layer 18, a second non-polarization layer. The magnetic layer 13b, the second high polarizability layer 19, the second fixed layer 12b, and the cap layer 16 are stacked in this order. Here, the first pinned layer 12 a has a SAF structure including the first magnetic layer 34, the nonmagnetic layer 35, and the second magnetic layer 36. A lower electrode 14 is provided on the bottom surface of the crystal orientation substrate 15, and an upper electrode 17 is provided on the upper surface of the cap layer 16. In this case, since the magnetizations 22a-1 and 22a-2 of the first and second magnetic layers 34 and 36 are in an antiparallel state, the leakage magnetic field from the first and second magnetic layers 34 and 36 is canceled, As a result, there is an effect of reducing the leakage magnetic field of the fixed layer 12a. Further, the exchange-coupled magnetic layers 34 and 36 improve thermal disturbance resistance as an effect of increasing the volume.

The laminated structure of the specific example 2-1 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Ru having a thickness of 5 nm. The fixed layer 12 a is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) ₁₅ having a (002) plane oriented as the first magnetic layer 34 and having a thickness of 20 nm, and the nonmagnetic layer 35 has a thickness. The second magnetic layer 36 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) _{15 having a} thickness of 15 nm. The first nonmagnetic layer 13a is made of Cu having a thickness of 5 nm. The recording layer 11 is composed of an artificial lattice [Co / Pt] 4 in which four periods are laminated with Co having a thickness of 0.3 nm and Pt having a thickness of 0.7 nm as one period. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 0.5 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.5 nm. Here, MgO has the (001) plane oriented. The second high polarizability layer 19 is made of Fe having a thickness of 1 nm. At this time, the (001) plane of Fe is oriented. The fixed layer 12b is made of Fe ₅₀ Pt ₅₀ having a (001) plane oriented with a thickness of 15 nm. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm. Here, the magnetoresistance ratio generated through the tunnel barrier layer TB is larger than the magnetoresistance ratio generated through the magnetic layer 13a.

  In this configuration, the change in magnetoresistance through MgO that is the tunnel barrier layer TB is larger than the change in magnetoresistance through Cu that is the first nonmagnetic layer 13a, and the recording layer 11 and the first high polarizability. Information is stored by the magnetization arrangement of the magnetic layer in which the layer 18 is integrated, the magnetic layer in which the second high polarizability layer 19 and the second fixed layer 12b are integrated. Further, by adopting a SAF structure in which the magnetic layer of the fixed layer 12a has a difference in film thickness, the magnetic moment of subtraction of the fixed layer 12a and the magnetic moment of the fixed layer 12b can be set in opposite directions. The leakage magnetic field from the fixed layers 12a and 12b applied to the recording layer 11 can be canceled out.

  The fixed layer 12a can also be formed using a RE-TM alloy. As described in the specific example 1-5, if a RE-TM alloy in which the magnetic moment of RE is larger than the magnetic moment of TM is used and, for example, a Co or CoFe alloy containing TM as a main component is laminated, Since the magnetic moment of Co and CoFe at the interface of the second nonmagnetic layer 13a can be made parallel to the magnetic moment of TM in the RE-TM alloy, the magnetic moment of Co and CoFe is changed to the magnetic force of the RE-TM alloy. This is because the moment (the magnetic moment of RE) can be set antiparallel.

(B) Specific example 2-2
In the MTJ element of Specific Example 2-2, the fixed layers 12a and 12b provided on both sides of the recording layer 11 have a single layer structure as shown in FIG. That is, since the specific example 2-2 is an example in which the fixed layer 12a in FIG. 10 has a single layer structure, the specific example 2-2 of the MTJ element 10 will be described below with reference to FIG.

  As shown in FIG. 10, the MTJ element 10 includes a crystal orientation substrate 15, a first fixed layer 12a, a first nonmagnetic layer 13a, a recording layer 11, a first high polarizability layer 18, a second non-polarization layer. The magnetic layer 13b, the second high polarizability layer 19, the second fixed layer 12b, and the cap layer 16 are stacked in this order. A lower electrode 14 is provided on the bottom surface of the crystal orientation substrate 15, and an upper electrode 17 is provided on the upper surface of the cap layer 16.

The stacked structure of Example 2-2 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The underlayer 15 for crystal orientation is a laminated film in which Co ₄₀ Fe ₄₀ B _{20 with} a film thickness of 0.5 nm, MgO with a film thickness of 0.5 nm, and Pt with a film thickness of 2 nm are sequentially formed. The fixed layer 12a is made of Fe ₅₀ Pt ₅₀ with a (001) plane oriented with a thickness of 10 nm, the first nonmagnetic layer 13a is made of Au with a (001) plane oriented with a thickness of 5 nm, and a recording layer 11 is made of Fe ₃₈ Cu ₁₂ Pt ₅₀ having a (001) plane oriented with a film thickness of 2 nm. The first high polarizability layer 18 is made of Fe having a thickness of 0.5 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.2 nm. Here, MgO has the (001) plane oriented. The second high polarizability layer 19 is made of Fe having a thickness of 1 nm. At this time, the (001) plane of Fe is oriented. The fixed layer 12b is made of Fe ₅₀ Pt ₅₀ with a (001) plane oriented with a thickness of 5 nm. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm.

  Here, the magnetoresistance ratio generated via the tunnel barrier layer TB is larger than the magnetoresistance ratio generated via the nonmagnetic layer 13a.

  The coercive force of the fixed layer 12a is larger than the coercive force of the fixed layer 12b, and the magnetization arrangement of the fixed layer 12a and the fixed layer 12b can be set antiparallel using the difference in coercive force. That is, it is sufficient to perform magnetization twice. First, by the first magnetic field application, the magnetization of the fixed layer 12a, the magnetization of the recording layer 11 and the first high polarizability layer 18 that behave as an integrated recording layer, and the second high that behaves as an integrated fixed layer. The magnetizations of the polarizability layer 19 and the fixed layer 12b are arranged in the same direction. Thereafter, the second magnetic field application is performed in the opposite direction to the first. This second applied magnetic field is larger than the coercivity of the second high polarizability layer 19 and the fixed layer 12b acting as an integrated fixed layer, and smaller than the coercive force of the fixed layer 12a. Thereby, the magnetization of the recording layer 11 and the first high polarizability layer 18 that behave as an integrated recording layer and the second high polarizability layer that behaves as an integrated fixed layer with respect to the magnetization direction of the fixed layer 12a. 19 and the magnetization of the fixed layer 12b are in opposite directions. In this way, the magnetization arrangement as shown in FIG. 9 can be realized.

  In this configuration, the change in magnetoresistance through MgO that is the tunnel barrier layer TB is larger than the change in magnetoresistance through Au that is the first nonmagnetic layer 13a, and the recording layer 11 and the first high polarizability. Information is stored by the magnetization arrangement of the magnetic layer in which the layer 18 is integrated, the magnetic layer in which the second high polarizability layer 19 and the second fixed layer 12b are integrated. Since the resistance through a metal film such as Au is low, even if a high polarizability layer is provided, the change in magnetoresistance is smaller than that of the tunnel barrier layer, so a high polarizability layer may be provided.

Similarly, in the MTJ element 10 described above, the fixed layer 12a has a thickness of 30 nm Tb ₂₂ (Fe ₇₁ Co ₂₉ ) ₇₈ , and the fixed layer 12b has a thickness of 30 nm Tb ₂₆ (Fe ₇₁ Co ₂₉ ) ₇₄ , The recording layer 11 is made of Tb ₂₂ (Fe ₇₁ Co ₂₉ ) ₇₈ having a thickness of 5 nm. Here, Tb ₂₄ (Fe ₇₁ Co ₂₉ ) ₇₆ is the compensation composition. In this case, the pinned layer 12a has a TM magnetic moment larger than the RE magnetic moment, and the pinned layer 12b has a RE magnetic moment larger than the TM magnetic moment. The magnetization arrangement equivalent to the magnetization arrangement of the nine fixed layers 12a and 12b can be realized. That is, since the TM magnetic moment of the fixed layer 12b is opposite to the RE magnetic moment, the entire fixed layer 12b is opposite to the magnetized direction (the direction of the TM magnetic moment), and further the second high polarization. Since the Fe that is the index layer 19 exchange-couples with the magnetic moment of TM, the direction is opposite to the magnetized direction.

  Each magnetic layer can be appropriately selected from ordered alloys, irregular alloys, artificial lattices, RE-TM alloys, and the like, as described in Examples 1-1 to 1-7.

  The fixed layer 12b may have a SAF structure, or the fixed layer 12a may have a single layer structure.

  In this specific example, the high polarizability layers 18 and 19 are inserted between the tunnel barrier layer TB and the recording layer 11 and between the tunnel barrier layer TB and the fixed layer 12b, respectively, and the nonmagnetic layer 13a and the recording layer 11 are inserted. And between the nonmagnetic layer 13a and the fixed layer 12a. However, a high polarizability layer may be provided between the recording layer 11 and the fixed layer 12a via the nonmagnetic layer 13a. In this case as well, the magnetoresistance ratio generated through the tunnel barrier layer TB needs to be larger than the magnetoresistance ratio generated through the magnetic layer 13a. Here, the nonmagnetic layers 13a and 13b may be insulators or tunnel barriers exhibiting a tunnel magnetoresistance effect. In this case, the magnetoresistance ratio can be differentiated by providing a high polarizability layer at the interface of only one of the tunnel barriers.

  In order to fix the fixed layer 12 in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

[1-3] Dual pin structure 2
11A and 11B are schematic cross-sectional views of an MTJ element having a dual pin structure 2 according to an embodiment of the present invention. The dual pin structure 2 MTJ element according to one embodiment of the present invention will be described below.

  As shown in FIGS. 11A and 11B, the MTJ element 10 includes a recording layer 11 made of a magnetic layer, first and second fixed layers 12a and 12b made of a magnetic layer, a recording layer 11 and a first layer. And a first nonmagnetic layer 13a sandwiched between one fixed layer 12a and a second nonmagnetic layer 13b sandwiched between the recording layer 11 and the second fixed layer 12b. . Further, the recording layer 11 has a SAF structure including a first magnetic layer 31, a nonmagnetic layer 32, and a second magnetic layer 33. In the so-called perpendicular magnetization type MTJ element 10, the magnetization directions 21-1 and 21-2 of the recording layer 11 and the magnetization directions 22a and 22b of the fixed layers 12a and 12b are perpendicular to the film surface.

  Here, the specific example 2-1 is different in that the magnetizations 22a and 22b of the first and second fixed layers 12a and 12b are in parallel magnetization arrangement. Correspondingly, it is desirable that the recording layer 11 has a SAF structure. However, as described in the specific example 1-5 and the like, the RE magnetic moment 41 is larger than the TM magnetic moment 42. And a RE-TM alloy layer 53 in which the RE magnetic moment 47 is smaller than the TM magnetic moment 48 may be laminated so that the magnetic moments of the two RE-TM alloys are antiparallel.

The MTJ element 10 has a TMR effect when the first and second nonmagnetic layers 13a and 13b are insulators, and has a GMR effect when the first and second nonmagnetic layers 13a and 13b are metal. . Here, when the first and second nonmagnetic layers 13a and 13b are insulators, MgO (magnesium oxide), AlO (aluminum oxide, for example, Al ₂ O ₃ ) or the like is used, and the first and second nonmagnetic layers are used. When the magnetic layers 13a and 13b are metal, Cu, Pt, Au or the like is used.

(Operation)
In the MTJ element 10 having the dual pin structure 2, the magnetic layer (the magnetic layer 31 and the fixed layer 12a of the recording layer 11) sandwiching the first nonmagnetic layer 13a or the magnetic layer (the recording layer) sandwiching the second nonmagnetic layer 13b. The magnetic layer 33 and the fixed layer 12b) of the layer 11 take a parallel or antiparallel arrangement. However, when viewed as the entire MTJ element 10, since both the parallel arrangement and the antiparallel arrangement exist simultaneously in FIGS. 11A and 11B, the overall magnetoresistance of both does not change. Therefore, when the fixed layers 12a and 12b are provided in parallel on both sides of the recording layer 11 in this way, the change in magnetoresistance via the first and second nonmagnetic layers 13a and 13b is differentiated. It is necessary to keep.

  For example, when the first nonmagnetic layer 13a is a tunnel barrier layer TB and the second nonmagnetic layer 13b is a metal layer, the change in magnetoresistance generated in the tunnel barrier layer TB is greater than the change in the metal layer. The magnetization arrangement via the first nonmagnetic layer 13a corresponds to information of “0” and “1”. Therefore, the parallel arrangement is shown in FIG. 11A and the antiparallel arrangement is shown in FIG. The second nonmagnetic layer 13b may be a tunnel barrier layer TB, and the first nonmagnetic layer 13a may be a metal layer. Here, the nonmagnetic layers 13a and 13b may be insulators or tunnel barriers exhibiting a tunnel magnetoresistance effect. In this case, the magnetoresistance ratio can be differentiated by providing a high polarizability layer at the interface of only one of the tunnel barriers.

  As described above, when the first nonmagnetic layer 13a is the tunnel barrier layer TB, the magnetization arrangement state of the two magnetic layers (the magnetic layer 31 of the recording layer 11 and the fixed layer 12a) is parallel (see FIG. )) Or an anti-parallel arrangement (FIG. 11B). Information of “0” and “1” is associated with the resistance value that changes depending on the magnetization arrangement state. Then, a spin-polarized current 30 is passed through the MTJ element 10 to change the magnetization direction 21 of the recording layer 11 and write information. However, spin-polarized electrons flow in the opposite direction to the spin-polarized current 30.

  Specifically, as shown in FIG. 11A, when a spin-polarized current 30 is passed from the second fixed layer 12b to the first fixed layer 12a, the spin-polarized electrons are transferred from the first fixed layer 12a. It flows to the second fixed layer 12b. In this case, since upward spins are mainly injected from the first fixed layer 12a, a torque acts to align the spins of the first magnetic layer 31 forming the recording layer 11 in parallel, and the recording layer 11 is In the process in which electrons flow from the second magnetic layer 33 to be formed to the second pinned layer 12b, the second pinned layer 12b is likely to transmit upward spins, so that the reflected spin-down electrons form the recording layer 11. The direction of the magnetization 21-1 of the first magnetic layer 31 forming the recording layer 11 is parallel to the magnetization 22a of the fixed layer 12a, and the second magnetic layer 33 is injected. The direction of the magnetization 21-2 of the layer 33 is antiparallel to the magnetization 22b of the fixed layer 12b. On the other hand, as shown in FIG. 11B, a case where a current is passed from the second pinned layer 12b to the first pinned layer 12a is also considered, and the first magnetic layer 31 forming the recording layer 11 has the same structure. The direction of the magnetization 21-1 is antiparallel to the magnetization 22a of the fixed layer 12a, and the direction of the magnetization 21-2 of the second magnetic layer 33 is parallel to the magnetization 22b of the fixed layer 12b.

(Magnetic material)
As the magnetic material of the magnetic layers 31 and 33 and the fixed layers 12a and 12b of the recording layer 11, the same material as the single pin structure can be used.

(effect)
According to the MTJ element 10 having the dual pin structure 2 according to the embodiment of the present invention, the same effect as the single pin structure can be obtained. Furthermore, since the pinned layers 12a and 12b are provided with a dual pin structure on both sides of the recording layer 11, the effect of reflection of spin-polarized electrons can be used more, so that the reversal current can be further reduced as compared with the single pin structure. Can do.

  A specific example of the MTJ element 10 having the dual pin structure 2 will be described below.

(A) Specific example 3
In the MTJ element of Example 3, the recording layer 11 has a SAF structure, and the magnetization directions of the first and second fixed layers 12a and 12b are parallel.

  FIG. 12 is a schematic cross-sectional view of a specific example 3 of the MTJ element according to the embodiment of the invention. A specific example 3 of the MTJ element 10 will be described below.

  As shown in FIG. 12, the MTJ element 10 includes a crystal orientation substrate 15, a first fixed layer 12a, a first high polarizability layer 18, a tunnel barrier layer TB, a second high polarizability layer 19, and a recording layer. 11, a second nonmagnetic layer 13 b, a second pinned layer 12 b, and a cap layer 16 are sequentially stacked. Here, the recording layer 11 has a SAF structure including the first magnetic layer 31, the nonmagnetic layer 32, and the second magnetic layer 33. A lower electrode 14 is provided on the bottom surface of the crystal orientation substrate 15, and an upper electrode 17 is provided on the upper surface of the cap layer 16. In this case, since the magnetizations 21-1 and 21-2 of the first and second magnetic layers 31 and 33 are in an antiparallel state, the leakage magnetic fields from the first and second magnetic layers 31 and 33 are offset, As a result, there is an effect of reducing the leakage magnetic field of the recording layer 11. Further, the exchange-coupled magnetic layers 31 and 33 improve thermal disturbance resistance as an effect of increasing the volume.

The layered structure of Example 3 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation base 15 is made of 3 nm thick Pt formed on 0.5 nm thick MgO. Here, the (001) plane of the MgO / Pt laminated film is oriented. The first fixed layer 12a is made of Fe ₅₀ Pt ₅₀ having a (001) plane oriented with a thickness of 20 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.5 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.5 nm. The second high polarizability layer 19 is made of Co ₆₃ Fe ₁₇ B ₁₀ having a thickness of 0.5 nm. The first magnetic layer 31 of the recording layer 11 is composed of an artificial lattice [Pd / Co] 4 in which Pd having a film thickness of 0.7 nm and Co having a film thickness of 0.3 nm are stacked for four periods. The first nonmagnetic layer 32 of the recording layer 11 is made of Ru having a thickness of 0.9 nm. The second magnetic layer 33 of the recording layer 11 is composed of an artificial lattice [Co / Pd] 2 in which Co having a film thickness of 0.3 nm and Pd having a film thickness of 0.7 nm are stacked for two periods. The second nonmagnetic layer 13b is made of MgO having a thickness of 0.8 nm. The second fixed layer 12b is made of Tb ₂₀ (Fe ₈₀ Co ₂₀ ) ₈₀ having a thickness of 30 nm. Here, in Tb ₂₀ (Fe ₈₀ Co ₂₀ ) ₈₀ , the magnetic moment of RE is smaller than the magnetic moment of TM, and the magnetization directions 22a and 22b of the first fixed layer 12a and the second fixed layer 12b are It has been adjusted to be parallel. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is composed of a laminated film in which Ru having a thickness of 10 nm is formed on Ta having a thickness of 10 nm. Here, the magnetoresistance ratio generated through the tunnel barrier layer TB in which the high polarizability layer is inserted at both interfaces is larger than the magnetoresistance ratio generated through the nonmagnetic layer 13b in which the high polarizability layer is not inserted. It has become.

  Each magnetic layer can be appropriately selected from ordered alloys, irregular alloys, artificial lattices, RE-TM alloys, and the like, as described in Examples 1-1 to 1-7.

  In this specific example, the high polarizability layers 18 and 19 are inserted between the tunnel barrier layer TB and the magnetic layer 31 of the recording layer 11 and between the tunnel barrier layer TB and the fixed layer 12a, respectively, and the nonmagnetic layer 13b. And the magnetic layer 33 of the recording layer 11 and between the nonmagnetic layer 13b and the fixed layer 12b. However, a high polarizability layer may be provided between the magnetic layer 33 of the recording layer 11 and the fixed layer 12b via the nonmagnetic layer 13b. Also in this case, the magnetoresistance ratio generated through the tunnel barrier layer TB needs to be larger than the magnetoresistance ratio generated through the nonmagnetic layer 13b.

  In order to fix the fixed layers 12a and 12b in one direction, an antiferromagnetic layer may be provided adjacently. As this antiferromagnetic layer, FeMn, NiMn, PtMn, PdMn, PtPdMn, RuMn, OsMn, IrMn, CrPtMn, etc. which are alloys of Mn and Fe, Ni, Pt, Pd, Ru, Os, Ir can be used. .

[1-4] Consideration of Saturation Magnetization of Recording Layer The various specific examples described above are examples of the configuration of a perpendicular magnetization film that realizes spin injection magnetization reversal. For example, in order to obtain a large capacity memory having a capacity of 256 Mbit or more, it is essential to reduce the write current. This write current is restricted by the current that can be passed through the write selection transistor, and magnetization reversal must be caused by a spin-polarized current lower than that. Along with miniaturization, when the gate length of the selection transistor is reduced, the current value of the write current is also reduced. For this reason, the write current density Jw must be suppressed to about 5 × 10 ⁶ A / cm ² or less, more preferably about 2 × 10 ⁶ A / cm ² or less.

  According to Non-Patent Documents 3 and 4, the reversal current can be roughly estimated by (Equation 1). However, the reversal current in (Equation 1) is for the case where the magnetization state is reversed from parallel (P) to antiparallel (AP). In the former case, the reversal current is larger when the magnetization state is reversed from parallel (P) to antiparallel (AP) than when the magnetization state is reversed from antiparallel (AP) to parallel (P). I am considering.

  Here, e is the elementary charge, Ms is the saturation magnetization of the reversing magnetic layer (recording layer 11), V is the volume, αdamp is the Gilbert damping constant, h is the Planck constant divided by 2π, and g ′ is g. The coefficient, g (θ), is a function of the polarizability by the efficiency of spin transfer at an angle θ formed by two magnetic materials. When the magnetization state is reversed from parallel (P) to antiparallel (AP), θ = 0, and when the magnetization state is reversed from antiparallel (AP) to parallel (P), θ = π. Hext is an external magnetic field, and Hani is an anisotropic magnetic field. The anisotropic magnetic field Hani is generally magnetic anisotropy caused by shape magnetic anisotropy and material. g ′ (g coefficient) is one of the coefficients linking the magnetic moment and the angular momentum, and is represented by g ′ = 1 for the orbital angular momentum and g ′ = 2 for the spin angular momentum. According to the physics of ferromagnets (above), Toshinori Kakukaku, p.73-79, the g coefficient is close to 2 for 3d transition metals.

  Assuming that the external magnetic field Hext is 0 and the shape anisotropy (∝Ms × t / w, t is the film thickness, w is the element width) is sufficiently smaller than the magnetic anisotropy magnetic field (Hk) due to the material, When 1) is transformed, (Equation 2) is obtained.

  In (Formula 2), the first term in parentheses represents the magnetic anisotropy energy density Ku, and the second term in parentheses represents the demagnetizing field energy.

  When the volume V is expressed by the cell area S and the film thickness t, V = S × t, so that the reversal current density is as shown in (Expression 3).

  Actually, in order to use the perpendicular magnetization film, the magnetic anisotropy energy density Ku due to the material, for example, the magnetocrystalline anisotropy energy density is large, the shape magnetic anisotropy is not used, and the element shape is about aspect 1. The use of is suitable for miniaturization. For this reason, as described above, the shape anisotropy may be sufficiently smaller than the magnetic anisotropic magnetic field caused by the material.

  In (Expression 3), a constant consisting of g ′, e, αdamp, h, and g (0) is A, and Ms · Hk / 2 is Ku, thereby obtaining (Expression 4).

  In (Expression 4), when the write current density is Jw, the following (Expression 5) needs to be satisfied.

  Furthermore, in order to set the magnetization direction perpendicular to the film surface, it is necessary to satisfy the following relationship (Equation 6).

  Therefore, from (Expression 5) and (Expression 6), the magnetic anisotropy energy density Ku needs to satisfy the relationship of (Expression 7).

FIGS. 13 (a) and 13 (b) and FIGS. 14 (a) and 14 (b) specifically illustrate the relationship of (Expression 7). FIGS. 13A and 13B and FIGS. 14A and 14B show the relationship between the magnetic anisotropy energy density Ku, the saturation magnetization Ms, and the film thickness t of the recording layer according to the embodiment of the present invention. Show. Here, FIGS. 13A and 14A show the case where the write current density Jw is 5 MA / cm ² , and FIGS. 13B and 14B show the write current density Jw of ² MA / cm ² . The case of cm ² is shown. Further, the case where the film thickness t of the recording layer 11 is 0.5 nm, 1 nm, 3 nm, 5 nm, and 10 nm is examined.

To achieve the above-mentioned ^{5MA / cm 2, 2MA / cm} 2 of the write current density Jw is illustrated in more (Equation 7), FIG. 13 (a) and 13 (b), FIG. 14 (a) and (b) It is necessary to set the magnetic anisotropy energy density Ku, the saturation magnetization Ms, and the film thickness t of the recording layer 11 in the hatched area.

  The relationship between g (θ) and the polarizability P of the giant magnetoresistance (GMR) in which the nonmagnetic layer is a conductive material such as Cu and Au and the tunnel magnetoresistance (TMR) in which the nonmagnetic layer is a tunnel barrier is ( It can be expressed by Equation 8) and Equation 9 respectively. The g coefficient g ′ is 2.

  In obtaining the relationship of FIGS. 13A and 13B, as an example, the damping constant αdamp was set to 0.01 and g (0) was set to 0.18. The upper limit of the magnetic anisotropic energy density Ku is defined by (Equation 7), and the first term is Jw / (2A · t). 14A and 14B show the case where the damping constant αdamp is 0.002. Comparing both with the same film thickness, when the damping constant αdamp is 1/5, the upper limit of the magnetic anisotropy energy density Ku is 5 times and the saturation magnetization Ms is expanded to √5 times. This can also be seen from (Equation 7). Similarly, the efficiency g (0) also changes the upper limit of the magnetic anisotropy energy density Ku and the range of the saturation magnetic field Ms. Therefore, as described above, the damping constant αdamp, the film thickness t, and the efficiency g (0) are important in determining appropriate ranges of the saturation magnetization Ms and the magnetic anisotropy energy density Ku. Is proportional to αdamp × t / g (0).

  The damping constant αdamp of the magnetic material may be about 0.001 to 0.5. The efficiency g (0) can be estimated from the polarizability P as shown in (Expression 8) and (Expression 9). In order to perform magnetization reversal by spin injection, it is desirable that the polarizability P is at least 0.1 or more, and the efficiency g (0) is about 0.026 and 0.05 in the case of GMR and TMR, respectively. When the polarizability P is 1, the efficiency g (0) is 0.25 for both GMR and TMR.

  Next, the film thickness t of the recording layer 11 will be examined. From (Equation 7), since the upper limit of the magnetic anisotropy energy density Ku decreases as the film thickness t increases, it becomes necessary to set the magnetic anisotropy energy density Ku small as the film thickness t increases. In order to realize perpendicular magnetization, the saturation magnetization Ms must also be reduced. This can be understood from FIGS. 13A and 13B and FIGS. 14A and 14B, and it is difficult to make the film thickness of the recording layer 11 larger than 5 nm. Therefore, it is desirable to set the film thickness of the recording layer 11 to 5 nm or less. Moreover, it is desirable that it is 0.5 nm or more from the viewpoint of in-plane uniformity.

  From the above, it is desirable that the film thickness t of the recording layer 11 satisfy the relationship of (Equation 10). In consideration of the case where the recording layer 11 is made of an artificial lattice having one period, the lower limit value of the film thickness of the recording layer 11 can be considered to be 0.2 nm or more. When the recording layer 11 is a laminated film exchange-coupled via a nonmagnetic layer, this corresponds to the film thickness of each layer that is exchange-coupled.

0.5 nm ≦ t ≦ 5 nm (Formula 10)
Considering the range of αdamp × t / g (0) from the above-described ranges of the damping constant αdamp, efficiency g (0), and film thickness t, 0.002 ≦ αdamp × t / g (0) ≦ 100. However, the unit of the film thickness t is expressed in nm. Considering these, as in FIGS. 13A and 13B and FIGS. 14A and 14B, the write current density Jw is 5 MA / cm ² with αdamp × t / g (0) as a parameter. The case of ² MA / cm ² is shown in FIGS. 15A and 15B, respectively.

Considering the film thickness t of the recording layer 11 in (Equation 10), the magnetic anisotropy energy density Ku will be examined. The magnetic anisotropy energy density Ku needs to be Ku> 2πMs ^{2 as} shown in (Formula 6) in order to become a perpendicular magnetization film. Magnetic materials that can minimize the saturation magnetization Ms are ferrimagnetic materials and antiferromagnetic materials, and the RE-TM alloy described above corresponds to this. The RE-TM alloy has a perpendicular magnetic anisotropy energy density Ku of 1 × 10 ⁵ erg / cc or more, which can be said to be the lower limit of the magnetic anisotropy energy density Ku.

On the other hand, the upper limit value of the magnetic anisotropy energy density Ku can be derived from the relationship shown in FIGS. That is, as shown in FIG. 15A, when the write current density Jw is 5 MA / cm ² , 4.1 × 10 ⁷ erg / cc which is the maximum in the hatched region is the upper limit of the magnetic anisotropic energy density Ku. Value. As shown in FIG. 15B, when the write current density Jw is 2 MA / cm ² , 1.6 × 10 ⁷ erg / cc, which is the maximum in the hatched region, is the upper limit of the magnetic anisotropic energy density Ku. Value.

From the above, the magnetic anisotropy energy density Ku, if the write current density Jw is 5MA / cm ² or less (11), when the write current density Jw is the 2 MA / cm ² or less a relationship (Equation 12) It is desirable to satisfy.

1 × 10 ⁵ erg / cc ≦ Ku ≦ 4.1 × 10 ⁷ erg / cc (Formula 11)
1 × 10 ⁵ erg / cc ≦ Ku ≦ 1.6 × 10 ⁷ erg / cc (Formula 12)
Next, the saturation magnetization Ms will be examined in consideration of the film thickness t of the recording layer 11 in (Equation 10). The saturation magnetization Ms can be derived from the relationship of FIGS. 15 (a) and 15 (b). That is, as shown in FIG. 15A, when the write current density Jw is 5 MA / cm ² , the saturation magnetization Ms is preferably 0 to 2090 emu / cc. As shown in FIG. 15B, when the write current density Jw is 2 MA / cm ² , the saturation magnetization Ms is preferably 0 to 1320 emu / cc.

From the above, the saturation magnetization Ms, if the write current density Jw is 5MA / cm ² or less (equation 13), the write current density Jw is the case of 2 MA / cm ² or less to satisfy the relationship of (Equation 14) should .

0 ≦ Ms ≦ 2090 emu / cc (Formula 13)
0 ≦ Ms ≦ 1320 emu / cc (Formula 14)
In summary, the write current density Jw is desirably 5 MA / cm ² or less. In the range of the film thickness t of the recording layer 11 in (Equation 10), the magnetic anisotropy energy density Ku is 1 × 10 6. ⁵ erg / cc to 4.1 × 10 ⁷ erg / cc is desirable, and the saturation magnetization Ms is desirably in the range of 0 to 2090 emu / cc. More preferably, the write current is desirably ² MA / cm ² or less, and the magnetic anisotropy energy density Ku is desirably in the range of 1 × 10 ⁵ erg / cc to 1.6 × 10 ⁷ erg / cc. The saturation magnetization Ms is preferably in the range of 0 to 1320 emu / cc.

  When the recording layer 11 is formed by laminating a highly polarized material and a magnetic layer, the entire laminated structure is regarded as one magnetic layer, that is, a recording layer. In this case, the saturation magnetization Ms, magnetic anisotropy energy density Ku, and film thickness t of the recording layer (high polarization material and magnetic layer) are the saturation magnetization, magnetic anisotropy energy density, and film thickness of the high polarizability material and magnetic layer. Assuming that the thicknesses are Ms1, Ku1, t1, Ms2, Ku2, and t2, respectively, it can be estimated as follows. In the case of three or more layers, it can be estimated in the same manner.

Ms = (Ms1 × t1 + Ms2 × t2) / t (Expression 15)
Ku = (Ku1 × t1 + Ku2 × t2) / t (Expression 16)
t = t1 + t2 (Expression 17)
Actually, the high polarizability material is made of Fe, Co, Ni, or an alloy containing at least one of these elements, and the saturation magnetization is at least about 500 emu / cc. The high polarizability material plays a role of improving the MR ratio, and for that purpose, it is desirable to set the film thickness to 0.5 nm or more. On the other hand, of the magnetic material that becomes the perpendicular magnetization film, the saturation magnetization can be reduced by the RE-TM alloy, and the saturation magnetization is 0 at the compensation point composition in which the magnetic moments of RE and TM are equal as described above. is there. As an example, a highly polarizable material having a saturation magnetization Ms1 of 800 emu / cc, a film thickness t1 of 0.5 nm, an anisotropic energy density Ku1 of 1000 erg / cc, a saturation magnetization Ms2 of 0 emu / cc, and an anisotropic energy density Ku2. Is a magnetic layer of 5 × 10 ⁵ erg / cc. In this case, when the film thickness t2 of the magnetic layer is 1.2 nm, the anisotropic energy density as the recording layer (highly polarized material and magnetic layer) is 3.53 × 10 ⁵ erg / cc. The saturation magnetization is 235 emu / cc, the film thickness is 1.7 nm, and Ku> 2πMs ² , which is a condition for forming a perpendicular magnetization film, is satisfied.

  Next, attention is paid to the saturation magnetization Ms of the recording layer 11 for examination. A case is considered where the lower limit value and the upper limit value are equal in (Expression 7) described above. That is, this is to find the intersection of FIGS. 15 (a) and 15 (b). Then, considering that it is desirable that the saturation magnetization Ms is smaller than this intersection, the relationship of (Equation 18) can be derived.

Ms <√ {Jw / (6πAt)} (Expression 18)
Further, as described above, when the recording layer 11 has a laminated structure of RE-TM alloy, the saturation magnetization Ms becomes zero. Therefore, it can be said that the lower limit value of the saturation magnetization Ms is zero.

  From the above, the saturation magnetization Ms of the recording layer 11 is expressed by (Equation 17) and (Equation 18) when the write current density Jw, the film thickness t of the recording layer 11 and the constant A are used.

0 ≦ Ms <√ {Jw / (6πAt)} (Equation 19)
A = g ′ · e · α / (h / 2π × g) (Equation 20)
Here, g ′ is the g coefficient, e is the elementary charge, α is the Gilbert damping constant, h is the Planck constant, and g is the efficiency of the spin transfer when the magnetizations of the two magnetic materials are arranged in parallel. .

  A specific example in consideration of the above-described write current density Jw and the like will be described below.

(A) Specific example 4-1
The MTJ element of Example 4-1 is similar to the stack of Example 1-4 shown in FIG. 3, and the recording layer 11 and the fixed layer 12 are made of a RE-TM alloy.

The stacked configuration of Specific Example 4-1 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 5 nm and Ru having a thickness of 5 nm. In this specific example, there is no equivalent to the crystal orientation substrate 15. The fixed layer 12 is made of Tb ₂₁ (Co ₈₄ Fe ₁₆ ) ₇₉ having a thickness of 30 nm. The first high polarizability layer 18 is made of Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of 2.0 nm. The tunnel barrier layer TB is made of MgO having a thickness of 0.7 nm. The second high polarizability layer 19 is made of Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of 1.0 nm. The recording layer 11 is made of Tb ₃₀ (Co ₈₄ Fe ₁₆ ) ₇₀ having a thickness of 5 nm. Here, Tb ₂₃ (Co ₈₄ Fe ₁₆ ) ₇₇ is a compensation composition. The cap layer 16 is made of Ru having a thickness of 3 nm. The upper electrode 17 is formed of a laminated film in which Ta having a thickness of 5 nm, Ru having a thickness of 5 nm, and Ta having a thickness of 100 nm are sequentially formed.

  When such an MTJ element 10 was processed into an element size of 0.14 um × 0.28 um and an RH loop was measured by the four-terminal method, the coercive force of the fixed layer 12 was 9.5 kOe, and the coercive force of the recording layer 11 was measured. The magnetic force was 6.5 kOe. Further, when the saturation magnetization Ms was measured from the MH loop with a vibrating sample magnetometer before processing, the fixed layer 12 was 100 emu / cc and the recording layer 11 was 80 emu / cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the second high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body.

Here, the saturation magnetization and magnetic anisotropy energy density of the recording layer 11 and the second high polarizability layer 19 are as follows. The saturation magnetization Ms2 and magnetic anisotropy energy density Ku2 of the recording layer 11 are −200 emu / cc and 5 × 10 ⁵ erg / cc, respectively, and the saturation magnetization Ms1 and magnetic anisotropy of the second high polarizability layer 19. The energy densities Ku1 are 1200 emu / cc and 1 × 10 ⁴ erg / cc, respectively. The reason why the saturation magnetization Ms2 of the recording layer 11 is expressed as negative is that the magnetic moment of TM is positive, and in this specific example, the magnetic moment of RE is larger than the magnetic moment of TM. This is because the magnetic moment of is opposite to the magnetic moment of TM. Therefore, when estimated as in (Expression 15) to (Expression 17), the saturation magnetization Ms and the magnetic anisotropy energy density Ku as a whole are 33 emu / cc and 4.2 × 10 ⁵ erg / cc, respectively. From this, the anisotropic magnetic field is estimated to be 25 kOe, which is larger than the measured coercive force. The reason why the coercive force is smaller than the anisotropic magnetic field is considered that reversal nuclei are formed due to non-uniformity of the film quality and the like, and magnetization reversal occurs due to domain wall movement. It is also conceivable that the saturation magnetization is shifted because the composition is not as set due to the mutual diffusion of CoFeB and TbCoFe.

The magnetoresistive ratio of the MTJ element 10 is 30% due to the contribution of the high polarizability layers 18 and 19. When this element was subjected to spin injection magnetization reversal, the reversal current density from the antiparallel (AP) state to the parallel (P) state was 4.5 × 10 ⁶ A / cm ² . Here, since the inversion current density from the antiparallel state to the parallel state was measured as g (π)> g (0) as apparent from (Equation 9), the parallel state was changed to the antiparallel state. This is because it is expected to be smaller than the reversal current density of ## EQU1 ## in order to avoid irreversible breakdown of the evaluation element.

It has been reported that the damping constant αdamp of Gd—CoFe which is an example of RE-TM is about 0.1. It is expected that the Tb—CoFe of the recording layer 11 of this specific example is similar. Further, since the magnetoresistance ratio is dependent on the bias voltage, it is expected to be about 20% at the time of inversion and g (π) is about 0.165. Dumping constant αdamp is 0.1, g (π) is 0.165, saturation magnetization Ms is 117 emu / cc, magnetic anisotropy energy density Ku is 4.2 × 10 ⁵ erg / cc, film thickness is 6 nm, and inversion The current density is estimated to be 9.4 × 10 ⁷ A / cm 2. On the other hand, as described above, the actually measured reversal current density is 4.5 × 10 ⁶ A / cm ² , which is greatly different from the estimate.

In view of this result, the inventor paid attention to the effect of the second high polarizability layer 19 laminated on the recording layer 11 made of Tb—CoFe. That is, it is said that the damping constant αdamp of Co ₄₀ Fe ₄₀ B ₂₀ which is the second high polarizability layer 19 is about 0.008, and the inversion current density is estimated as it is as it is 8.2 × 10 ⁶ A. / Cm ² , indicating a relatively good match. That is, a magnetic material having a small damping constant αdamp (Co ₄₀ Fe ₄₀ B ₂₀ : αdamp = 0.008 used as the second high polarizability layer 19) and a magnetic material having a large damping constant αdamp (Tb used for the recording layer 11). -CoFe: αdamp = 0.1) is laminated, a magnetic material having a small damping constant αdamp receives a larger spin torque than a magnetic material having a large damping constant αdamp. It has been found that there is an effect of reducing.

  As described above, when a magnetic material having a small damping constant αdamp and a large magnetic material are laminated, it has been found that there is an effect of reducing current, but a material having a small damping constant αdamp is, for example, Fe. The damping constant αdamp of Fe is reported to be about 0.002, and the polarizability P is reported to be about 0.4. For this reason, the index αdamp × t / g (0) described above is estimated to be about 0.01 with the film thickness t (nm) being 1 nm. Therefore, from FIGS. 15A and 15B, when the index αdamp × t / g (0) is 0.01, the saturation magnetization Ms and the anisotropic energy density Ku are estimated to be Jw = 5 MA / cm 2. In the case of Ms <934 emu / cc, Ku <8.2 × 10 6 erg / cc, and Jw = 2 MA / cm 2, it is understood that the ranges of Ms <591 emu / cc and Ku <3.3 × 10 6 erg / cc are preferable.

  The case where the magnetic material having a small damping constant αdamp and the magnetic material having a large damping constant αdamp as described above are laminated is an example. For example, the following form may be adopted.

  A form in which a magnetic material having a small damping constant αdamp and a magnetic material having a large damping constant αdamp are mixed may be used. For example, as shown in FIGS. 16 (a) and 16 (b), a material having a large damping constant αdamp may be used as a base material, and a material having a small damping constant αdamp may be dispersed. FIGS. 16 (c) and 16 (d) may be used. As shown, a material having a large damping constant αdamp may be dispersed using a material having a small damping constant αdamp as a base material. In FIGS. 16B and 16D, the dispersed material is a cylindrical shape, but the material is not limited to this, and may be a shape such as a sphere, a rectangular parallelepiped, or a cube. Not limited to.

  Further, it can be seen from (Equation 1) that it is effective to reduce the volume of the recording layer in order to further reduce the reversal current density. For example, a film in which a material having a small damping constant αdamp is dispersed is used. A laminated film of a material having a large damping constant αdamp (so-called granular film) may be used, or a laminated film of a material having a large damping constant αdamp dispersed therein (so-called granular film) and a material having a small damping constant may be used. Furthermore, a laminated film of a film in which a material having a small damping constant αdamp is dispersed (so-called granular film) and a film in which a material having a large damping constant is dispersed (so-called granular film) may be used.

  In order to become a perpendicularly magnetized film, it is necessary to have a relatively large perpendicular magnetic anisotropy energy, but a material exhibiting a large magnetic anisotropy is an alloy composed of Co, Fe, and Ni used as a high polarizability material. The damping constant αdamp is larger than that of the material. Therefore, a stacked form of a material having a small damping constant αdamp and a material having a large damping constant αdamp is more desirable for the spin injection magnetization reversal of the perpendicular magnetization film.

  Specific examples in the case of using a magnetic material having a small damping constant αdamp and a magnetic material having a large damping constant αdamp as described above will be shown below.

As a magnetic material having a small damping constant αdamp, there is a magnetic alloy having a low damping constant based on Fe. Examples of this magnetic alloy include an alloy containing at least Fe, and it is desirable that Fe be contained in an amount of 40 at% or more. The magnetic alloy may be a Heusler alloy known as a half-metal material, and examples thereof include Co ₂ MnSi, Co ₂ MnGe, Co ₂ CrAl, Co ₂ (Cr—Fe) Al, and Co ₂ FeSi.

The large magnetic material damping constant Arufadamp, there are magnetic alloy of L1 ₀ structure having a high perpendicular magnetic anisotropy. As this magnetic alloy, for example, an alloy containing any one of Fe—Pt, Fe—Pd, Co—Pt, Co—Pd, and Mn—Al as a main component can be cited. The magnetic alloy may be a ternary or higher alloy such as Fe-Pt-X, Fe-Pd-X, or Co-Pt-X.

  As a magnetic material having a small damping constant αdamp and a magnetic material having a large damping constant, a material having a lattice constant a with good matching with the MgO (100) plane is preferable. For example, as a material having a lattice constant of 0.9a to 1.1a and 0.9 × √2a to 1.1 × √2a on a (001) plane of cubic or tetragonal crystal, the crystal structure is a face centered cubic crystal Alternatively, it is preferably made of a face-centered tetragonal crystal and having an a-axis lattice constant in the range of 3.79A to 4.63A, 5.36A to 6.55A. In addition, as a cubic or tetragonal (001) plane material having a lattice constant of 0.9 × √2 / 2a to 1.1 × √2 / 2a, the crystal structure is body-centered cubic or body-centered tetragonal Preferably, the a-axis lattice constant is in the range of 2.68A to 3.28A.

  In the above description, the magnitude relationship between a material having a large damping constant αdamp and a material having a small damping constant αdamp may be established in comparison of the damping constant αdamp of both materials. Further, a reference value (for example, 0.01) of the damping constant αdamp is defined. When the reference value is larger than this reference value, the material is defined as a material having a large damping constant αdamp. May be defined.

  As described in Specific Example 4-1, when a magnetic layer having a large damping constant αdamp and a magnetic layer having a small damping constant αdamp are stacked, a material having a large damping constant αdamp has perpendicular magnetic anisotropy energy. It is desirable to magnetize in the direction perpendicular to the film surface. It is desirable that the material having a small damping constant αdamp has a small anisotropy energy so that it is easily affected by the perpendicular magnetic anisotropy of the magnetic layer having a large damping constant αdamp. It is desirable that a material having a small damping constant αdamp and a material having a large damping constant αdamp are exchange coupled. Of course, a material having perpendicular magnetic anisotropy and a small damping constant αdamp may be used.

  When a magnetic layer having a large damping constant αdamp and a magnetic layer having a small damping constant αdamp are stacked, it is desirable that the magnetic layer having a small damping constant αdamp is positioned on the tunnel barrier layer TB side. For example, in the case of the structure shown in FIG. 3, a magnetic layer having a small damping constant αdamp may be provided at the position of the second high polarizability layer 19 and a magnetic layer having a large damping constant αdamp may be provided at the position of the recording layer 11. Thereby, the effect of reducing the reversal current density can be enhanced. Note that a magnetic layer having a large damping constant αdamp can be arranged on the tunnel barrier layer TB side. A laminated structure of tunnel barrier layer TB / second high polarizability layer 19 / magnetic layer having a small damping constant αdamp / magnetic layer having a large damping constant αdamp may be used.

  When a magnetic layer having a large damping constant αdamp and a magnetic layer having a small damping constant αdamp are stacked, the number of layers is not limited to two, and three or more layers may be used. Also in this case, as described above, it is desirable to stack a magnetic layer having a small damping constant αdamp on the tunnel barrier layer TB side.

  When the MTJ element 10 has a dual pin structure, the recording layer 11 is sandwiched between the nonmagnetic layers 13a and 13b, but a magnetic layer having a small damping constant αdamp is positioned at the interface between the nonmagnetic layers 13a and 13b and the recording layer 11, respectively. Is desirable. For example, in the structure of FIG. 10, if a magnetic layer having a small damping constant αdamp is provided at the position of the high polarizability layer 18 adjacent to the tunnel barrier layer TB, and a magnetic layer having a large damping constant αdamp is provided at the position of the recording layer 11. Good. Although there is a high polarizability material on the tunnel barrier layer TB side from the viewpoint of the magnetoresistance ratio, a magnetic layer having a small damping constant αdamp may be further provided between the recording layer 11 and the nonmagnetic layer 13a. It is desirable that spin torque acts effectively on both interfaces of the recording layer 11, and it is sufficient that there is a difference in magnetoresistance ratio between the nonmagnetic layers 13a and 13b.

(B) Specific example 4-2
The MTJ element of specific example 4-2 is the same as the laminated structure of specific example 1-2 shown in FIG. 3, and the recording layer 11 is made of RE-TM alloy and the fixed layer 12 is made of CoPtCr.

The stacked configuration of Specific Example 4-2 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Ru having a thickness of 5 nm. The fixed layer 12 is made of (Co ₇₈ Pt ₁₂ Cr ₁₀ ) ₈₅ — (SiO ₂ ) ₁₅ having a (002) plane oriented with a thickness of 30 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 2.0 nm. The tunnel barrier layer TB is made of MgO having a thickness of 1.0 nm. The second high polarizability layer 19 is made of Co ₆₀ Fe ₂₀ B ₂₀ having a thickness of 1.0 nm. The recording layer 11 is made of Tb ₂₁ (Co ₈₄ Fe ₁₆ ) ₇₉ having a thickness of 4 nm. Here, Tb ₂₃ (Co ₈₄ Fe ₁₆ ) ₇₇ is a compensation composition. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is formed of a laminated film in which Ta having a thickness of 5 nm, Ru having a thickness of 5 nm, and Ta having a thickness of 100 nm are sequentially formed.

  When such an MTJ element 10 was processed into an element size of 0.1 μm × 0.1 μm and an RH loop was measured by a four-terminal method, the coercive force of the fixed layer 12 was 4.0 kOe, and the coercive force of the recording layer 11 was The magnetic force was 1200 Oe. Further, when the saturation magnetization Ms was measured from the MH loop with a vibrating sample magnetometer before processing, the fixed layer 12 was 500 emu / cc and the recording layer 11 was 400 emu / cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the second high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body.

Here, the saturation magnetization and magnetic anisotropy energy density of the recording layer 11 and the second high polarizability layer 19 are as follows. The saturation magnetization Ms2 and the magnetic anisotropy energy density Ku2 of the recording layer 11 are 100 emu / cc and 7 × 10 ⁵ erg / cc, respectively. The saturation magnetization Ms1 and the magnetic anisotropy energy of the second high polarizability layer 19 The densities Ku1 are 1100 emu / cc and 1 × 10 ⁴ erg / cc, respectively. Therefore, when estimated as in (Expression 15) to (Expression 17), the saturation magnetization Ms and the magnetic anisotropic energy density Ku as a whole are 300 emu / cc and 5.6 × 10 ⁵ erg / cc, respectively. From this, the anisotropic magnetic field is estimated to be 3.7 kOe, which is larger than the measured coercive force. The reason why the coercive force is smaller than the anisotropic magnetic field is considered that reversal nuclei are formed due to non-uniformity of the film quality and the like, and magnetization reversal occurs due to domain wall movement.

The magnetoresistive ratio of the MTJ element 10 is 120% due to the contribution of the high polarizability layers 18 and 19. When this element was subjected to spin injection magnetization reversal, the average current density was 8.4 × 10 ⁶ A / cm ² .

The following MTJ element 10 was examined with the aim of further reducing the current density. The second high polarizability layer 19 is made of Ni ₈₀ Fe ₂₀ having a thickness of 0.5 nm, and the recording layer 11 is made of Tb ₂₆ (Co ₈₄ Fe ₁₆ ) ₇₄ having a thickness of 2 nm. As described above, when the RH loop and MH loop were measured, the coercive force and saturation magnetization of the recording layer 11 were 1400 Oe and 70 emu / cc. The saturation magnetization Ms1 and magnetic anisotropy energy density Ku1 of Ni ₈₀ Fe ₂₀ are 800 emu / cc, 1000 erg / cc, the saturation magnetization Ms2 of Tb ₂₆ (Co ₈₄ Fe ₁₆ ) _{74 having} a thickness of 2.0 nm, and the magnetic anisotropy, respectively. The energy densities were −100 emu / cc and 5.0 × 10 ⁵ erg / cc, respectively. As estimated above, the saturation magnetization Ms and magnetic anisotropy energy density Ku of the recording layer 11 as a whole including the high polarizability layer 19 are 80 emu / cc and 4.0 × 10 ⁵ erg / cc, respectively. Similarly, the anisotropic magnetic field is estimated to be 10 kOe. In this case, the magnetoresistance ratio of the MTJ element 10 is 60% due to the contribution of the high polarizability layers 18 and 19. When this element was subjected to spin injection magnetization reversal, the average current density was 2.7 × 10 ⁶ A / cm ² .

(C) Specific example 4-3
The MTJ element of specific example 4-3 is the same as the stacked example of specific example 1-2 shown in FIG. 3, and the recording layer 11 is made of an artificial lattice and the fixed layer 12 is made of FePt.

The stacked configuration of Specific Example 4-3 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation underlayer 15 is made of Pt having a thickness of 10 nm formed on MgO having a thickness of 0.3 nm. Here, the (001) plane of the MgO / Pt laminated film is oriented. The fixed layer 12 is made of Fe ₅₀ Pt ₅₀ having a (001) plane oriented with a thickness of 20 nm. The first high polarizability layer 18 is made of Co ₆₂ Fe ₂₂ B ₁₆ having a thickness of 1.5 nm. The tunnel barrier layer TB is made of MgO having a film thickness of 0.8 nm, and (001) plane of MgO is oriented. The second high polarizability layer 19 is made of Co having a thickness of 0.3 nm. Here, the film forming conditions are adjusted so that a Co (001) surface having a bcc structure is formed. The recording layer 11 is made of an artificial lattice [Pt / CoCr] 2 in which Pt having a film thickness of 2.0 nm and Co ₈₀ Cr ₂₀ having a film thickness of 0.3 nm are stacked for two periods. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is formed of a laminated film in which Ta having a thickness of 5 nm, Ru having a thickness of 5 nm, and Ta having a thickness of 100 nm are sequentially formed.

  When such an MTJ element 10 was processed to an element size of 0.1 μm × 0.1 μm and an RH loop was measured by the four-terminal method, the coercive force of the fixed layer 12 was 7.0 kOe, and the coercive force of the recording layer 11 was The magnetic force was 1000 Oe. Further, when the saturation magnetization was measured from the MH loop with a vibrating sample magnetometer before processing, the fixed layer 12 was 1000 emu / cc and the recording layer 11 was 220 emu / cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the second high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body.

Here, the saturation magnetization and magnetic anisotropy energy density of the recording layer 11 and the second high polarizability layer 19 are as follows. The saturation magnetization Ms2 and magnetic anisotropy energy density Ku2 of the recording layer 11 are 140 emu / cc and 5 × 10 ⁵ erg / cc, respectively. The saturation magnetization Ms1 and the magnetic anisotropy energy density Ku1 of the second high polarizability layer 19 Are 1400 emu / cc and 1 × 10 ⁶ erg / cc, respectively. Accordingly, when estimated as in (Expression 15) to (Expression 17), the saturation magnetization Ms and the magnetic anisotropic energy density Ku as a whole are 220 emu / cc and 5.3 × 10 ⁵ erg / cc, respectively. Here, the saturation magnetization of the artificial lattice was converted from the film thickness of the entire Pt / CoCr. From this, the anisotropic magnetic field is estimated to be 4.9 kOe, which is larger than the measured coercive force. The reason why the coercive force is smaller than the anisotropic magnetic field is considered that reversal nuclei are formed due to non-uniformity of the film quality and the like, and magnetization reversal occurs due to domain wall movement.

The magnetoresistive ratio of the MTJ element 10 is 80% due to the contribution of the high polarizability layers 18 and 19. When this element was subjected to spin injection magnetization reversal, the average current density was 7.7 × 10 ⁶ A / cm ² .

(D) Specific Example 4-4
The MTJ element of specific example 4-4 is the same as the stacked example of specific example 1-2 shown in FIG. 3, and both the recording layer 11 and the fixed layer 12 are made of an FePt alloy.

The stacked configuration of Specific Example 4-4 of the MTJ element 10 is as follows. The lower electrode 14 is made of Ta having a thickness of 10 nm. The crystal orientation substrate 15 has a structure in which Co ₄₀ Fe ₄₀ B _{20 with} a film thickness of 0.5 nm, MgO with a film thickness of 0.5 nm, and Pt with a film thickness of 3 nm are sequentially formed. Here, the (001) plane of the MgO / Pt laminated film is oriented. The fixed layer 12 is made of Fe ₅₀ Pt ₅₀ having a (001) plane oriented with a thickness of 10 nm. The first high polarizability layer 18 is made of Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of 2 nm. The tunnel barrier layer TB is made of MgO having a film thickness of 0.8 nm, and (001) plane of MgO is oriented. The second high polarizability layer 19 is made of Fe ₈₀ B ₂₀ having a thickness of 0.5 nm, and the (001) plane is oriented. The recording layer 11 is made of Fe ₁₅ Ni ₃₅ Pt ₅₀ having a thickness of 2.0 nm, and the (001) plane is oriented. The cap layer 16 is made of Pt having a thickness of 3 nm. The upper electrode 17 is formed of a laminated film in which Ta having a thickness of 5 nm, Ru having a thickness of 5 nm, and Ta having a thickness of 100 nm are sequentially formed.

  When such an MTJ element 10 was processed into an element size of 0.1 μm × 0.1 μm and an RH loop was measured by the four-terminal method, the coercive force of the fixed layer 12 was 5.0 kOe, and the coercive force of the recording layer 11 was The magnetic force was 1 kOe. Further, when saturation magnetization was measured from the MH loop with a vibrating sample magnetometer before processing, the fixed layer 12 was 1000 emu / cc and the recording layer 11 was 450 emu / cc. However, since the fixed layer 12 and the first high polarizability layer 18 are exchange-coupled, and the recording layer 11 and the second high polarizability layer 19 are exchange-coupled, each acts as one magnetic layer. The coercive force and saturation magnetization are values when viewed as one magnetic body.

Here, the saturation magnetization and magnetic anisotropy energy density of the recording layer 11 and the second high polarizability layer 19 are as follows. The saturation magnetization Ms2 and magnetic anisotropy energy density Ku2 of the recording layer 11 are 250 emu / cc and 2 × 10 ⁶ erg / cc, respectively. The saturation magnetization Ms1 and magnetic anisotropy energy density Ku1 of the second high polarizability layer 19 Are 1300 emu / cc and 1 × 10 ³ erg / cc, respectively. Therefore, when estimated as in (Expression 15) to (Expression 17), the saturation magnetization Ms and the magnetic anisotropic energy density Ku as a whole are 460 emu / cc and 1.6 × 10 ⁶ erg / cc, respectively. Here, the saturation magnetization of the artificial lattice was converted from the film thickness of the entire Pt / CoCr. From this, the anisotropic magnetic field is estimated to be 7 kOe, which is larger than the measured coercive force. The reason why the coercive force is smaller than the anisotropic magnetic field is considered that reversal nuclei are formed due to non-uniformity of film quality and the like, and magnetization reversal occurs due to domain wall movement.

The magnetoresistive ratio of the MTJ element 10 is 120% due to the contribution of the high polarizability layers 18 and 19. When this element was subjected to spin injection magnetization reversal, the average current density was 5.7 × 10 ⁶ A / cm ² .

  The coercive force Hc is a magnetic parameter that serves as a standard for magnetization reversal. However, when the magnetization reversal is ideal in a single magnetic domain, Hc and Hk are equal. However, in reality, it does not become a single magnetic domain, and Hc is said to be smaller than about 0.3 times Hk. The specific example described above is the coercive force Hc. Actually, Hk is larger than the coercive force and satisfies Hk> 4πMs. Hk can be evaluated from a magnetic anisotropy energy density Ku at a Hk = 2 Ku / Ms with a tockle meter.

  In Specific Example 4-1 to Specific Example 4-4 described above, the MTJ element 10 having a single pin structure is taken as an example. However, the relationship between the above (Formula 1) to (Formula 20) and FIGS. 13 to 15 is dual. It can also be applied to pin structures.

[2] Magnetic Random Access Memory Next, an example in which the perpendicular magnetization type MTJ element 10 described above is applied to a magnetic random access memory as a memory cell storage element will be described.

(A) Embodiment 1
The first embodiment is an example of a magnetic random access memory including a select transistor type memory cell.

  FIG. 17 is a schematic cross-sectional view of the magnetic random access memory according to the first embodiment of the present invention. The magnetic random access memory according to the first embodiment will be described below.

  As shown in FIG. 17, a gate electrode 63 is formed on a semiconductor substrate (for example, a silicon substrate) 61 via a gate insulating film 62, and source / drain diffusion layers 64a, 64a are formed in the semiconductor substrate 61 on both sides of the gate electrode 63. 64b is formed. As described above, the transistor Tr functioning as a switching element for reading is provided.

  A lead wiring 66 is connected to the drain diffusion layer 64 b through a contact 65. A lower wiring 14 is formed on the lead wiring 66, and a perpendicular magnetization type MTJ element 10 is formed on the lower wiring 14. An upper wiring 17 is formed on the MTJ element 10, and a wiring 67 is formed on the upper wiring 17. On the other hand, a wiring 69 is connected to the source diffusion layer 64b through a contact 68.

  When the MTJ element 10 is formed on the lead wiring 66, it is desirable to form the lower electrode 14 at one end of the MTJ element 10 as described above. The lower electrode 14 only needs to ensure electrical conduction between the MTJ element 10 and the transistor Tr, and is preferably made of a material having a low resistivity. Further, in order to form the MTJ element 10 on the lower electrode 14, it is desirable to form a material having as high a smoothness as possible. For example, Ta, TaN, etc., or a laminated film thereof may be used. Further, after the lower electrode 14 is formed, there may be a flattening step by CMP (Chemical Mechanical Polish) in order to improve smoothness.

  The write operation is performed as follows. First, the MTJ element 10 is selected from a plurality of MTJ elements in the memory cell array using a switching element. That is, the potential of the gate electrode 63 of the transistor Tr connected to the MTJ element 10 is turned on. Accordingly, a write current flows from the wiring 67 to the wiring 69 or from the wiring 69 to the wiring 67. With this write current, spin-polarized electrons are injected into the MTJ element 10 to realize spin injection writing.

  On the other hand, the read operation is performed as follows. In the read operation, a read current is supplied from the wiring 67 to the wiring 69 or from the wiring 69 to the wiring 67 through the same path as the above-described writing operation. Here, the tunnel resistance of the MTJ element 10 is read, and “1” and “0” are determined.

  According to the first embodiment as described above, by using the perpendicular magnetization type MTJ element 10, it is possible to miniaturize the MTJ element 10 without increasing the switching magnetic field Hsw. Further, as described above, even if the MTJ element 10 is miniaturized, the reversal magnetic field does not increase. Therefore, the large capacity (for example, 256 Mbit or more) having the fine MTJ element 10 of 90 nm or less that cannot be realized by the conventional magnetic random access memory. Magnetic random access memory can be realized. Further, by adopting spin injection writing, writing and reading can be performed through the same path, so that the cell area can be remarkably reduced.

(B) Embodiment 2
When the MTJ element 10 is used, the leakage magnetic field from each magnetic layer may affect the adjacent cell. Therefore, in the second embodiment, a soft magnetic film is provided on the wiring in order to reduce the influence of the leakage magnetic field.

  FIG. 18 is a schematic cross-sectional view of a magnetic random access memory according to the second embodiment of the present invention. The magnetic random access memory according to the second embodiment will be described below.

  As shown in FIG. 18, soft magnetic films 71, 72, and 73 are provided on wirings 66, 67, and 69 located above and below the MTJ element 10, respectively. Specifically, the soft magnetic film 73 covers the bottom surface of the wiring 66 on the MTJ element 10 side, the soft magnetic film 72 covers the top surface of the lead wiring 66 on the MTJ element 10 side, and the soft magnetic film 71 forms the MTJ element of the wiring 69. The upper surface on the 10 side is covered.

  Such soft magnetic films 71, 72, 73 are different from the magnetic yoke wiring structure known in MRAM. That is, the magnetic yoke is provided to efficiently supply the MTJ element with the magnetic field generated from the current flowing through the write wiring, so that the entire area around the write wiring is not covered and the surface facing the MTJ element is not covered. Do not provide. On the other hand, the soft magnetic films 71, 72, 73 of the present embodiment are provided in order to prevent the leakage magnetic field generated from the MTJ element 10 from affecting neighboring wirings. That is, since the soft magnetic films 71, 72, and 73 of the present embodiment are intended to absorb the leakage magnetic field from the MTJ element 10, the wiring 67 above the MTJ element 10 is disposed on the bottom surface of the wiring 67. The wirings 66, 69 below the MTJ element 10 are provided with soft magnetic films 71, 72, 73 on the top surfaces of the wirings 66, 69, which are different from the yoke wiring.

  The soft magnetic films 71, 72, 73 are not limited to being formed only on the top or bottom surfaces of the wirings 66, 67, 69. For example, the soft magnetic films 71, 72, 73 may be further provided on the side surfaces of the wirings 66, 67, 69, or may circulate all of the surfaces around the wirings 66, 67, 69. Further, the soft magnetic film may be formed not only on the wirings 66, 67, and 69 but on a part such as a base that is close to the MTJ element 10. For example, the MTJ element 10 may be sandwiched from above and below (thickness direction) with a soft magnetic film. A soft magnetic film may be formed in contact with the side surface of the MTJ element 10. In this case, it is desirable to use an insulating soft magnetic film so that the recording layer and the fixed layer of the MTJ element 10 do not short-circuit.

  The soft magnetic films 71, 72, 73 are made of a magnetic layer made of any one element of Ni, Fe, and Co or an alloy containing at least one of these elements. For example, NiFe is preferable, but CoNi, FeCo can also be used. Further, the soft magnetic films 71, 72, and 73 may have a so-called SAF structure like NiFe / Ru / NiFe.

  According to the second embodiment as described above, the same effect as in the first embodiment can be obtained. Furthermore, by providing the soft magnetic films 71, 72, 73 on the wirings 66, 67, 69, the leakage magnetic field from the MTJ element 10 can be sucked, so that the influence on the adjacent cells can be reduced.

[3] Application of Magnetic Random Access Memory In the magnetic random access memory according to the embodiment of the present invention described above, the structure of the memory cell can be applied to various types.

(A) Application example 1
FIG. 19 is a block diagram of a DSL data path portion of a digital subscriber line (DSL) modem as an application example 1 of the magnetic random access memory according to the embodiment of the present invention. Application example 1 will be described below.

  As shown in FIG. 19, the modem includes a programmable digital signal processor (DSP) 100, analog-to-digital (A / D) converters and digital-to-analog (D / A) converters 110 and 120, a transmission driver 130, and a receiver amplifier. 140 etc. are included.

  In FIG. 19, the bandpass filter is omitted. Instead, select the modem according to the line code program (encoded subscriber line information, transmission conditions, etc. executed by the DSP) (line code: QAM, CAP, RSK, FM, AM, PAM, DWMT, etc.) , Various types of optional memory are provided for holding a program to operate. As this memory, a magnetic random access memory (MRAM) 170 and an EEPROM (Electrically Erasable Programmable ROM) 180 described above are shown.

  In this application example, two types of memories, the magnetic random access memory 170 and the EEPROM 180, are used as memories for holding the line code program. However, the EEPROM 180 may be replaced with an MRAM. That is, it is possible to use only MRAM instead of using two types of memories.

(B) Application example 2
FIG. 20 is a block diagram of a part for realizing a communication function in a mobile phone terminal as an application example 2 of the magnetic random access memory according to the embodiment of the present invention. Application example 2 will be described below.

  As shown in FIG. 20, a communication unit 200 that realizes a communication function includes a transmission / reception antenna 201, an antenna duplexer 202, a reception unit 203, a baseband processing unit 204, a DSP (Digital Signal Processor) 205 used as an audio codec, a speaker. (Receiver) 206, microphone (transmitter) 207, transmitter 208, frequency synthesizer 209, and the like.

  In addition, the mobile phone terminal 300 includes a control unit 220 that controls each unit of the mobile phone terminal. The control unit 220 is a microcomputer formed by connecting a CPU (Central Processing Unit) 221, a ROM 222, the magnetic random access memory (MRAM) 223 of the above embodiment and application example 1, and a flash memory 224 via a CPU bus 225. It is. The ROM 222 stores data necessary for programs executed by the CPU 221 and display fonts in advance.

  The MRAM 223 is mainly used as a work area, and the CPU 221 stores data being calculated during execution of the program as needed, and temporarily stores data exchanged between the control unit 220 and each unit. It is used when doing. Further, the flash memory 224 stores, for example, the previous setting conditions even when the power of the mobile phone terminal 300 is turned off, and when using the same setting when the power is turned on next time, the flash memory 224 The setting parameters are stored. Thereby, even if the power of the mobile phone terminal is turned off, the stored setting parameters are not lost.

  The mobile phone terminal 300 also includes an audio data reproduction processing unit 211, an external output terminal 212, an LCD (Liquid Crystal Display) controller 213, a display LCD 214, and a ringer 215 that generates a ringing tone. The audio data reproduction processing unit 211 reproduces audio data input to the mobile phone terminal 300 (or audio data stored in an external memory 240 described later). The reproduced audio data is taken out by transmitting it to a headphone, a portable speaker or the like via the external output terminal 212. The LCD controller 213 receives display information from the CPU 221 via the CPU bus 225, for example, and converts it into LCD control information for controlling the LCD 214. With this control information, the LCD 214 is driven and information is displayed.

  The mobile phone terminal 300 also includes interface circuits (I / F) 231, 233, 235, an external memory 240, an external memory slot 232, a key operation unit 234, and an external input / output terminal 236. An external memory 240 such as a memory card is inserted into the external memory slot 232. The external memory slot 232 is connected to the CPU bus 225 via the interface circuit 231. Thus, by providing the slot 232 in the mobile phone terminal 300, information inside the mobile phone terminal 300 is written in the external memory 240, or information stored in the external memory 240 (for example, voice data) is stored in the mobile phone terminal. It is possible to input to 300. The key operation unit 234 is connected to the CPU bus 225 via the interface circuit 233. Key input information input from the key operation unit 234 is transmitted to the CPU 221, for example. The external input / output terminal 236 is connected to the CPU bus 225 via the interface circuit 235, and inputs various information from the outside to the mobile phone terminal 300 or outputs information from the mobile phone terminal 300 to the outside. Functions as a terminal.

  In this application example, the ROM 222, the MRAM 223, and the flash memory 224 are used. However, either or both of the flash memory 224 and the ROM 222 can be replaced with the MRAM.

(C) Application example 3
FIG. 21 shows an application example 3 in which the magnetic random access memory according to one embodiment of the present invention is applied to an electronic card (MRAM card) that stores media content such as smart media. Hereinafter, application example 3 will be described.

  As shown in FIG. 21, the MRAM card body 400 includes an MRAM chip 401. In the card body 400, an opening 402 is formed at a position corresponding to the MRAM chip 401, and the MRAM chip 401 is exposed. The opening 402 is provided with a shutter 403 so that the MRAM chip 401 is protected by the shutter 403 when the MRAM card is carried. The shutter 403 is made of a material having an effect of shielding an external magnetic field, for example, ceramic. When transferring data, the shutter 403 is opened and the MRAM chip 401 is exposed. The external terminal 404 is for taking out content data stored in the MRAM card to the outside.

  22 and 23 show a top view and a cross-sectional view of a card insertion type data transfer device (electronic device) for transferring data to the MRAM card of FIG. Hereinafter, a card insertion type data transfer apparatus will be described.

  As shown in FIGS. 22 and 23, the data transfer device 500 has a storage portion 500a. The storage unit 500a stores the first MRAM card 550. The storage unit 500 a is provided with an external terminal 530 that is electrically connected to the first MRAM card 550, and the data of the first MRAM card 550 is rewritten using the external terminal 530.

  The second MRAM card 450 used by the end user is inserted from the insertion portion 510 of the data transfer device 500 and pushed in by the stopper 520 until it stops. The stopper 520 is also used as a member for aligning the first MRAM card 550 and the second MRAM card 450. When the second MRAM card 450 is arranged at a predetermined position, a data rewrite control signal is supplied from the data rewrite control unit of the first MRAM card 550 to the external terminal 530, and the data stored in the first MRAM card 550 is stored. Is transferred to the second MRAM card 450.

  FIG. 24 is a cross-sectional view of a fitting type data transfer apparatus for transferring data to the MRAM card of FIG. The inset type data transfer apparatus will be described below.

  As shown in FIG. 24, the fitting type data transfer device is placed so as to fit the second MRAM card 450 on the first MRAM card 550 with the stopper 520 as a target, as indicated by the arrows in the figure. Type. Since the transfer method is the same as that of the card insertion type data transfer apparatus described above, description thereof is omitted.

  FIG. 25 is a sectional view of a slide type data transfer device for transferring data to the MRAM card of FIG. A slide type data transfer apparatus will be described below.

  As shown in FIG. 25, the slide-type data transfer device is provided with a saucer slide 560 in the data transfer device 500, like the CD-ROM drive or DVD drive, and this saucer slide 560 is indicated by an arrow in the figure. Move to. When the tray slide 560 moves to the position indicated by the broken line in the drawing, the second MRAM card 450 is placed on the tray slide 560, and the second MRAM card 450 is conveyed into the data transfer device 500. The point of transfer so that the tip of the second MRAM card 450 comes into contact with the stopper 520 and the transfer method are the same as those in the card insertion type data transfer device described above, and thus the description thereof is omitted.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention when it is practiced. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.

  DESCRIPTION OF SYMBOLS 10 ... MTJ element, 11 ... Recording layer, 12, 12a, 12b ... Fixed layer, 13, 13a, 13b, 32, 35, 54 ... Nonmagnetic layer, 14 ... Lower electrode, 15 ... Base for crystal orientation, 16 ... Cap Layer, 17 ... upper electrode, 18, 19 ... high polarizability layer, 21, 21-1, 21-2 ... magnetization direction of recording layer, 22, 22a, 22b, 22-1, 22-2 ... magnetization of fixed layer Direction, 30 ... spin polarized current, 31, 33, 34, 36 ... magnetic layer, 51, 52, 53 ... RE-TM alloy layer, 61 ... semiconductor substrate, 62 ... gate insulating film, 63 ... gate electrode, 64a ... Source diffusion layer, 64b ... Drain diffusion layer, 65, 68 ... Contact, 66 ... Lead-out wiring, 67, 69 ... Wiring, 71, 72, 73 ... Soft magnetic film, TB ... Tunnel barrier layer, Tr ... Transistor, 100 ... Programmable Digital Signal processor 110 ... Analog-digital converter 120 ... Digital-analog converter 130 ... Transmission driver 140 140Receiver amplifier 170,223 ... MRAM 180 ... EEPROM 200 ... Communication unit 201 ... Transmission / reception antenna 202 ... Antenna duplexer 203 ... receiving unit 204 ... baseband processing unit 205 ... DSP 206 ... speaker 207 ... microphone 208 ... transmitting unit 209 ... frequency synthesizer 211 ... audio data reproduction processing unit 212 ... external output Terminals, 213 ... LCD controller, 214 ... LCD, 215 ... linger, 220 ... control unit, 221 ... CPU, 222, ROM, 224 ... flash memory, 231,233,235 ... interface circuit, 232 ... external memory slot, 234 ... -Operation unit, 236 ... external output terminal, 240 ... external memory, 300 ... mobile phone terminal, 400 ... memory card, 401 ... MRAM chip, 402 ... opening, 403 ... shutter, 404 ... external terminal, 450 ... second MRAM card, 500 ... transfer device, 510 ... insertion section, 520 ... stopper, 530 ... external terminal, 550 ... first MRAM card, 560 ... dish slide.

Claims (20)

A magnetoresistive element in which information is recorded by flowing spin-polarized electrons through a magnetic material,
A first pinned layer comprising a magnetic material and having a first magnetization oriented perpendicular to the film surface;
A recording layer comprising a magnetic material, having a second magnetization oriented in a direction perpendicular to the film surface, and capable of reversing the direction of the second magnetization by the action of the spin-polarized electrons;
A first non-magnetic layer provided between the first fixed layer and the recording layer and having a first surface facing the first fixed layer and a second surface facing the recording layer When,
A first magnetic metal layer provided between the first surface of the first nonmagnetic layer and the first pinned layer and including one or more elements of Fe, Co, and Ni;
A second magnetic metal layer that is provided between the second surface of the first nonmagnetic layer and the recording layer and includes one or more elements of Fe, Co, and Ni, and
The first nonmagnetic layer includes MgO with a (001) plane oriented,
At least one of the first and second magnetic metal layers includes a magnetic material selected from Co, Fe, a Co—Fe alloy, and a Fe—Ni alloy having a bcc structure and having a (001) plane oriented.
At least one of the first fixed layer and the recording layer is an alloy containing Co and at least one of Cr, Ta, Nb, V, W, Hf, Ti, Zr, Pt, Pd, Fe, and Ni. ,
The recording layer and the second magnetic metal layer are exchange coupled to each other;
A magnetoresistive effect element, wherein a damping constant of the second magnetic metal layer is smaller than a damping constant of the recording layer. A magnetoresistive element in which information is recorded by flowing spin-polarized electrons through a magnetic material,
A first pinned layer comprising a magnetic material and having a first magnetization oriented perpendicular to the film surface;
A recording layer comprising a magnetic material, having a second magnetization oriented in a direction perpendicular to the film surface, and capable of reversing the direction of the second magnetization by the action of the spin-polarized electrons;
A first non-magnetic layer provided between the first fixed layer and the recording layer and having a first surface facing the first fixed layer and a second surface facing the recording layer When,
A first magnetic metal layer provided between the first surface of the first nonmagnetic layer and the first pinned layer and including one or more elements of Fe, Co, and Ni;
A second magnetic metal layer that is provided between the second surface of the first nonmagnetic layer and the recording layer and includes one or more elements of Fe, Co, and Ni, and
The first nonmagnetic layer includes MgO with a (001) plane oriented,
At least one of the first and second magnetic metal layers includes a magnetic material selected from Co, Fe, a Co—Fe alloy, and a Fe—Ni alloy having a bcc structure and having a (001) plane oriented.
At least one of the first fixed layer and the recording layer includes a first layer containing at least one of Fe, Co, and Ni, and Cr, Pt, Pd, Ir, Rh, Ru, Os, Re, Au, Second layers containing at least one of Cu are alternately stacked,
The recording layer and the second magnetic metal layer are exchange coupled to each other;
A magnetoresistive effect element, wherein a damping constant of the second magnetic metal layer is smaller than a damping constant of the recording layer. A second pinned layer comprising a magnetic material and having a third magnetization oriented perpendicular to the film surface;
A second nonmagnetic layer provided between the second pinned layer and the recording layer and having a third surface facing the second pinned layer and a fourth surface facing the recording layer The magnetoresistive effect element according to claim 1, further comprising: A second pinned layer comprising a magnetic material and having a third magnetization oriented perpendicular to the film surface;
A second nonmagnetic layer provided between the second pinned layer and the recording layer and having a third surface facing the second pinned layer and a fourth surface facing the recording layer When,
The first magnetoresistive ratio generated between the recording layer and the first fixed layer via the first nonmagnetic layer is obtained from the recording layer and the second fixed layer via the second nonmagnetic layer. The magnetoresistive effect element according to claim 1, wherein the magnetoresistive effect element is larger than a second magnetoresistive ratio generated in the magnetic field.   The magnetoresistive element according to claim 3, wherein the first and second nonmagnetic layers are insulators and exhibit a tunnel magnetoresistive effect. At least one of the layers comprising the magnetic material has a first magnetic layer, a second magnetic layer, and a third nonmagnetic layer provided between the first and second magnetic layers. ,
The magnetoresistive element according to any one of claims 1 to 5, wherein the first and second magnetic layers are antiferromagnetically coupled to each other.   3. The magnetoresistive element according to claim 2, wherein at least one of the first fixed layer and the recording layer has a structure in which layers containing Co and layers containing Pd are alternately stacked.   The magnetoresistive effect element according to claim 1, wherein the recording layer is oriented in a (111) plane.   One or more of the layers comprising the magnetic material have a structure in which the magnetic body portion and the nonmagnetic body portion are separated by segregation of the nonmagnetic body portion. The magnetoresistive effect element of any one of these.   At least one of the first and second magnetic metal layers includes one or more elements of Fe, Co, Ni and one or more elements of B, Nb, Zr, Ta, V, W. The magnetoresistive effect element according to claim 1, comprising an alloy, wherein the ferromagnetic alloy has a bcc structure.   11. The magnetoresistive effect element according to claim 1, wherein a film thickness of the second magnetic metal layer is thinner than a film thickness of the first magnetic metal layer. The magnetoresistive effect element according to any one of claims 1 to 11,
A magnetic random access memory comprising: a write wiring for supplying a current to the magnetoresistive element. The magnetoresistive effect element according to any one of claims 1 to 11,
A write wiring for applying a current to the magnetoresistive element;
A magnetic random access memory comprising: a soft magnetic film that covers at least a part of the write wiring and absorbs a magnetic field leaked from the magnetoresistive effect element. The magnetoresistive effect element according to any one of claims 1 to 11,
A write wiring for applying a current to the magnetoresistive element;
A magnetic random access memory comprising: a first and a second soft magnetic film that sandwich the magnetoresistive effect element from a thickness direction and absorb a magnetic field leaked from the magnetoresistive effect element. A semiconductor chip having the magnetoresistive effect element according to any one of claims 1 to 11,
A card portion having a window for housing the semiconductor chip and exposing the semiconductor chip;
A shutter comprising a material that opens and closes the window and has a magnetic shielding effect;
An electronic card comprising: a terminal provided in the card portion and electrically connecting the semiconductor chip to the outside of the card portion. A storage unit that stores the electronic card according to claim 15;
An electronic device comprising: a terminal provided in the housing portion, electrically connected to the electronic card, and supplying a data rewrite control signal of the electronic card. A method of manufacturing a magnetoresistive effect element in which information is recorded by flowing spin-polarized electrons through a magnetic material,
A first pinned layer comprising a magnetic material and having a first magnetization oriented perpendicular to the film surface;
A recording layer comprising a magnetic material, having a second magnetization oriented in a direction perpendicular to the film surface, and capable of reversing the direction of the second magnetization by the action of the spin-polarized electrons;
A first non-magnetic layer provided between the first fixed layer and the recording layer and having a first surface facing the first fixed layer and a second surface facing the recording layer When,
A first magnetic metal layer provided between the first surface of the first nonmagnetic layer and the first pinned layer and including one or more elements of Fe, Co, and Ni;
Provided between the second surface of the first non-magnetic layer and the recording layer, exchange coupled with the recording layer, having a damping constant smaller than the damping constant of the recording layer, Fe, Co, Forming a laminated structure including a second magnetic metal layer containing one or more elements of Ni, and
The first nonmagnetic layer is formed of MgO having a (001) plane oriented,
Forming at least one of the first and second magnetic metal layers with a magnetic material selected from Co, Fe, Co—Fe alloy, and Fe—Ni alloy having a bcc structure and having a (001) plane oriented,
Alternatingly, first layers containing at least one of Fe, Co, Ni and second layers containing at least one of Cr, Pt, Pd, Ir, Rh, Ru, Os, Re, Au, Cu A method of manufacturing a magnetoresistive element, wherein at least one of the first fixed layer and the recording layer is formed by laminating the layers. A magnetoresistive effect element according to claim 17 is formed,
A write wiring for supplying a current to the magnetoresistive effect element is formed. A method of manufacturing a magnetic random access memory. A magnetoresistive effect element according to claim 17 is formed,
Forming a write wiring for applying a current to the magnetoresistive element;
A method of manufacturing a magnetic random access memory, comprising: forming a soft magnetic film that covers at least a part of the write wiring and absorbs a magnetic field leaked from the magnetoresistive effect element. A magnetoresistive effect element according to claim 17 is formed,
Forming a write wiring for applying a current to the magnetoresistive element;
A method of manufacturing a magnetic random access memory, comprising sandwiching the magnetoresistive effect element from a thickness direction and forming first and second soft magnetic films that absorb a magnetic field leaked from the magnetoresistive effect element.

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